GM RPO option code lookup
Nobody holds one option code — a build sheet gives you a column of them. Paste the whole row in and this reads back what each code is, the years it was offered and which cars it went on. Chevrolet Camaro, Chevelle, Nova and full-size, 1960s to early 1980s. Where two references disagreed, the row says both.
The build sheet will not last. The record can.
Buildbook keeps what the codes only start: the parts, the receipts, the machine shop specifications, the photographs and the hours, as one Build Book that stays with the car. Free to keep, and it takes a minute to start.
Where the codes are
For a 1960s or 1970s car this is where the codes are. It was tucked into the car on the line — over the fuel tank, under the rear seat, inside a seat spring, on top of the glovebox, under the carpet. Fragile, often gone, and the single most valuable piece of paper in the car.
The Service Parts Identification label, on later cars: a sticker in the glovebox, on the console lid or inside the trunk lid, printing the paint code and then every RPO the car was built with in one block. Read the whole block in here at once.
If either survived, they list the options as codes and prices. Photograph them and keep the photograph with the car, because both fade and both go missing in a house move.
The cowl tag on the firewall carries paint, interior trim, the plant and the build date — not RPO codes. That is a different plate with a different code set, and the cowl tag decoder reads it.
The table
All 113 codes, printed in full and grouped the way you read a build sheet: what makes it go, then what stops and steers it, then what it looks like and what it is like to sit in.
The Z-codes and option groups — the ones that decide what the car is called.
Special Performance Package
Camaro
The signature Camaro performance package (small-block, heavy suspension, quick-ratio steering); reproduction Z28 badges and stripe kits are commonly slapped on non-Z28 cars, so cross-check the SPID/build sheet before trusting exterior badging alone.
Super Sport (SS) package
Camaro
Bundled performance engine and suspension content with SS exterior/interior trim; could not be combined with the Z28 option on Camaro. Frequently cloned onto base cars with add-on SS emblems and hood stripes.
Rally Sport (RS) package
Camaro
Best known for the split/hideaway headlight nose treatment; RS content was purely appearance and could be combined with Z28 or SS, which is why an "RS/Z28" or "RS/SS" combo is not automatically suspicious.
SS 396/402 body conversion
Chevelle
Internal "SS conversion" code; on many 1970 build sheets ZL3 appears in place of the Z25 SS option code, a documented plant-to-plant naming inconsistency worth knowing before assuming a car is mis-tagged.
Super Sport (SS 396/402) equipment package
Chevelle
The classic Chevelle SS package; 1970 build sheets often list ZL3 instead of Z25 for the same content, so absence of "Z25" on a 1970 sheet does not disprove an SS car.
Sources differ: macswebs.com shows Z25 used in both 1969 and 1970; ss396.com describes the Z25 "SS396/402 Special Equipment Package" as "available only in 1970."
SS equipment / SS 454
Chevelle
In 1970 Z15 specifically denoted the SS 454 big-block package; from 1971-72 it was reused as the general "SS Equipment" trim code independent of engine size, so the meaning of Z15 depends heavily on model year.
Displacement, carburettor and the horsepower the code was rated at.
350 CID V8, 4-barrel carburetor
Chevelle, Nova (also widely used GM-wide, e.g. base Z28 engine some years)
Standard 4-bbl 350 small-block; horsepower fell over the run with emissions tuning (SS396.com's Nova page cites ~300 hp for the late-1960s/1970s Nova application). Also referenced on the 1969 Camaro cowl-tag options table (camaros.org/numbers.shtml, already used as a body-file source) as the "ENGINE REINF ASY" / SS350 code.
350 CID V8, 2-barrel carburetor
Chevelle, Camaro
Entry-level 350 small-block, lower compression/carb than L48. NastyZ28 gives 245 hp for the Camaro application.
250 CID inline-6
Chevelle, Camaro
Base six-cylinder engine; NastyZ28 calls it "6 Cylinder Engine, 250 CID (base engine)" for Camaro with no year restriction. SS396.com's Chevelle powertrain list also names L22 as the 250 CID six.
307 CID V8
Chevelle
Base small V8 for entry-level Chevelles in the early 1970s.
327 CID V8
Chevelle, Nova
Common mid-tier 327 small-block; SS396.com's Nova page describes it as "commonly 275 hp." Not one of the codes explicitly requested but included as a well-sourced base V8.
396 CID V8, High Performance (350 hp)
Chevelle, Camaro (SS package engine choice)
Mid-level 396 big-block, step below L78. NastyZ28's Camaro-specific entry gives 350 hp and ties the code to the SS option; that source's year annotation ("1970 - SS Only") differs from the Chevelle-table year range, most likely because it documents the Camaro SS engine slate rather than Chevelle build years — see CONFLICTS section for the discrepancy as stated.
396 CID V8 (325 hp)
Chevelle, Camaro
Standard/base big-block offered under the SS396 umbrella; SS396.com's Camaro breakdown gives 325 hp explicitly, matching the commonly cited figure for this engine.
396 CID V8, Special High Performance (375 hp)
Chevelle, Camaro, Nova
Top-tier solid-lifter 396; both Chevelle and Camaro sources agree on the 375 hp rating and the CID. SS396.com's Nova page also lists L78 (with L34) as the 396 big-block offered "'68-'70 Nova SS (availability varies by year)."
Sources differ: Both references agree on the displacement and the 375 hp, and disagree on the Camaro years. ss396.com reads "L78 | 1967-1969 | 396ci/375hp big block"; nastyz28.com reads "396ci, 375hp Turbo-jet V8 (1970 - SS Only)." Not resolved here.
327 CID V8, Special High Performance (350 hp)
Chevelle, Nova
High-output solid-lifter 327; SS396.com's Nova page singles out the 1966 Nova SS L79 as a landmark performance car.
427 CID V8, iron block (425 hp)
Camaro (COPO 9561), Chevelle (COPO 9561 dealer orders)
The "iron block" COPO 427, distinct from the aluminum ZL1 (COPO 9560); Camaro Research Group's detailed COPO report states the engine at "427/425 hp" and documents dealers (Yenko, Berger, Dana, Nickey, Baldwin-Motion) who ordered L72 COPO 9561 cars in both Camaro and Chevelle form. SS396.com's Chevelle page corroborates "ultra-rare COPO Chevelles had L72 427 engines."
427 CID V8, all-aluminum, COPO 9560
Camaro (COPO 9560)
The rarest and most expensive 1969 Camaro engine option — an all-aluminum 427 originally intended for Can-Am/Corvette racing use, ordered via Central Office Production Order 9560. Camaro Research Group's report states the AMA-filed horsepower figure was 430 but that "The ZL-1 was a legitimate 500+ horsepower engine" in as-built form, and documents engine codes "MV"/"MX" as RPO ZL1. SS396.com's Camaro breakdown corroborates "COPO 9560 – Central Office Production Order for ZL1 427ci aluminum big block."
454 CID V8, High Performance
Chevelle (base engine for the Z15 SS454 option), also full-size Chevrolet and Corvette
The standard 454 offered under the SS454 (Z15) package; ChevyWorld's production-numbers page states LS5 was "the base 454 cid engine for the 1970 SS454 Equipment (RPO Z15)" with 4,298 sold in 1970 at $503.45, and that in 1971-72 the Z15 became more of a dress-up package that could pair with LS5 or smaller engines.
454 CID V8, Special High Performance (450 hp)
Chevelle
The legendary 450 hp/500 lb-ft solid-lifter 454, sold under the Z15 SS454 option; 4,475 built in 1970 per ChevyWorld's production tally. Heacock Classic's article independently states "The 450 horsepower LS6 was the most powerful engine offered in 1970" and cites the RPO Z15 SS 454 Equipment package pricing.
350 CID V8, solid-lifter high performance (255-360 hp depending on year/measurement standard)
Camaro Z28 only (this era's LT1; not to be confused with the 1990s LT1)
The Z28-exclusive high-output small-block for the second-generation Camaro's first three years; NastyZ28 gives the hp range as 255-360 (reflecting the gross-to-net rating changes across 1970-1972), and SS396.com's Camaro breakdown confirms "Z28 – Now powered by LT1 350ci small-block in 1970-72."
Manual gearsets, automatics and the shift linkage codes.
4-speed manual transmission, wide ratio
Chevelle, Camaro, Nova
Camaro Research Group's detailed transmission page states "M20 was the generic RPO for a 4-speed transmission" and "The wide-ratio Muncie 4-speed transmission was marketed under RPO M20," available with most performance engines except that 1967 L78/Z28 cars came only with M21. Chevellestuff's year-by-year table shows M20 offered every Chevelle model year 1964-1972.
4-speed manual transmission, close ratio
Chevelle, Camaro
Camaro Research Group states "The close-ratio version of the Muncie 4-speed was RPO M21" and that in 1967 it was the only 4-speed available behind the L78 and Z28 engines.
4-speed manual transmission, heavy-duty close ratio ("Rock Crusher")
Chevelle, Camaro
Camaro Research Group: "the heavy-duty close-ratio 4-speed was RPO M22 ... limited to just the solid-lifter engines"; notes the distinctive gear-mesh whine that earned the "Rock Crusher" nickname. NastyZ28 confirms the M22 designation for Camaro as "4-speed heavy-duty close ratio (1970-1972)."
Turbo Hydra-Matic 400 (TH400) 3-speed automatic
Chevelle, Camaro, Nova
The heavy-duty 3-speed automatic used behind big-blocks and high-performance small-blocks. NastyZ28 confirms "M40 – Transmission, Turbo Hydra-Matic automatic, TH400" for Camaro.
Powerglide 2-speed automatic
Chevelle, Camaro, Nova
The base/entry automatic transmission, phased out on Chevelle after 1972.
Heavy-duty 3-speed manual transmission (Borg-Warner)
Chevelle, Camaro
Camaro Research Group states plainly: "The HD three-speed standard transmission was RPO M13 in 1967-68 (manufactured by Borg-Warner), but was MC1 (manufactured by Muncie) in 1969," and that M13 was required with a floor shift on SS396 models, optional on SS350.
Heavy-duty 3-speed manual transmission (Muncie)
Chevelle, Camaro
Muncie-built replacement for the Borg-Warner M13 heavy-duty 3-speed, introduced for the 1969 model year per Camaro Research Group's transmission page.
Floor-shift transmission linkage option
Chevelle, Camaro
Camaro Research Group describes M11 as the floor-shift-without-console option available with the 1968 SS396's TH400, distinct from the console-mounted shifter that came with RPO D55. Chevellestuff's Chevelle table lists M11 simply as "Floor Shift Transmission" for 1971-1972 — the same underlying meaning (a floor-mounted shift linkage code) applied on a different model/year.
Ratios and positraction. Several of these are ratio-only codes.
Rear axle ratio option (meaning changed by year/model)
Chevelle, Camaro
GM reused the G92 code for different specific purposes across the era — a fixed 3.08:1 highway gear on 1960s Chevelles, then a high-altitude-compliance gear in the mid-1970s Camaro, then a performance gear later. This is a year/model-dependent meaning shift, not a factual disagreement between the two sources (their stated year ranges do not overlap).
Rear axle, 3.31:1 ratio
Chevelle
Corroborated numerically by a GM-wide axle-code reference (differentials.com), which independently lists "G94 | Axle Rear (Ratio) | 3.31."
Rear axle, 3.55:1 ratio
Chevelle
Corroborated by differentials.com's GM-wide list: "G96 | Axle Rear (Ratio) | 3.55."
Rear axle, 2.73:1 ratio
Chevelle
Corroborated by differentials.com's GM-wide list: "G97 | Axle Rear (Ratio) | 2.73."
Rear axle, 4.56:1 ratio
Chevelle
Corroborated by differentials.com's GM-wide list: "G82 | Axle Rear (Ratio) | 4.56."
Rear axle, 4.10:1 ratio
Chevelle
Corroborated by differentials.com's GM-wide list: "G84 | Axle Rear (Ratio) | 4.10."
Rear axle, 3.07:1 ratio
Chevelle
Corroborated by differentials.com's GM-wide list: "H01 | Axle Rear (Ratio) | 3.07."
Rear axle, 3.73:1 ratio
Chevelle
Corroborated by differentials.com's GM-wide list: "H05 | Axle Rear (Ratio) | 3.73."
Rear axle, 2.73:1 ratio
Camaro
NastyZ28 lists "GU2: Axle - Rear (2.73 Ratio)"; corroborated by differentials.com's GM-wide list, same ratio.
Rear axle, 3.08:1 ratio
Camaro
NastyZ28 lists "GU4: Axle - Rear (3.08 Ratio)"; corroborated by differentials.com's GM-wide list, same ratio.
Rear axle, 3.42:1 ratio
Camaro
NastyZ28 lists "GU6: Axle - Rear (3.42 Ratio)"; corroborated by differentials.com's GM-wide list, same ratio. SS396.com's Camaro breakdown also mentions "GU6 = 3.42 gears" for third-generation cars, a third loose corroboration.
Power assist and front discs.
Vacuum Power Brake Equipment
Camaro, Chevelle, Nova
Standard power-brake option, included automatically with Z28 on Camaro; extremely common, so its presence alone does not indicate a special car.
Front disc brakes
Camaro, Chevelle
Front disc conversion; on 2nd-gen Camaro it became standard equipment rather than a check-box option, which is why some build sheets omit it entirely.
Front disc brakes
Chevelle
Front-disc RPO code used after J52 was phased out on Chevelle.
Sources differ: macswebs.com shows JL2 present on 1970-72 Chevelle build sheets; ss396.com states JL2 front disc brakes were "introduced in 1972." Treat 1970-71 JL2 Chevelle cars as needing extra build-sheet verification.
The heavy-duty and special-performance spring and bar packages.
Special/Heavy-Duty front and rear suspension
Chevelle
Base-level performance suspension upgrade offered every year of the A-body run; often ordered alongside F41 in later years, so check which of the two actually appears on the build sheet.
Special Performance Front and Rear Suspension
Camaro, Chevelle, Nova
Firmer springs/shocks and larger sway bars; a genuinely desirable handling option across all three GM intermediate/compact lines and often paired with F40 language in period documentation, which causes confusion between the two codes.
Power assist, quick-ratio boxes and the steering columns.
Power steering
Camaro, Chevelle, Nova
One of the most common options ordered on any V8 A/F/X-body; unremarkable alone, but its absence on a big-block car is a flag worth checking against the build sheet.
Tilt steering wheel/column
Chevelle, Camaro
Standard tilt-column option offered continuously through the era covered here.
Wood-grained plastic steering wheel
Chevelle
Deluxe wood-grain wheel used before the later N30/NK-series deluxe wheels replaced it.
Sources differ: macswebs.com (Chevelle-specific) calls N34 a "Wood-Grained Plastic" steering wheel for 1964-69; cjponyparts' cross-division truck list calls the same code a "Sports-Styled Steering Wheel." Likely the same RPO letter was reused for a different wheel design on truck lines - treat the wood-grain reading as authoritative for A-body cars.
Deluxe steering wheel
Chevelle
Mid-grade steering wheel upgrade offered between base and wood-grain/tilt wheels.
Deluxe steering wheel
Chevelle
Replaced N30 as the mid-grade wheel option in the early 1970s.
Sources differ: macswebs.com (Chevelle) simply calls NK2 a "Deluxe Steering Wheel"; nastyz28.com (2nd-gen Camaro) describes NK2 as a "custom black" steering wheel. The two lines likely shared the code for closely related but not identical wheels.
Sport steering wheel (4-spoke)
Chevelle, Camaro
Four-spoke sport wheel; description matches closely between the Chevelle and Camaro reference lists.
Wheel and tyre options.
Cast aluminum wheels
Camaro
Factory alloy wheel option; reproduction "N90-style" wheels are widely sold, so confirm casting marks/backspacing against period photos if authenticity matters.
Simulated magnesium wheel trim cover
Chevelle
Faux-mag wheel cover, not an actual alloy wheel; frequently mislabeled as "mag wheels" by sellers.
Wheel trim cover (bright metal)
Camaro, Chevelle
Base bright hubcap style, offered continuously; low collector value but very commonly missing/swapped on surviving cars.
Wheel trim ring
Camaro, Chevelle
Standard equipment on Z28; bright trim rings around Rally-style wheels.
Rally wheels with trim rings
Chevelle, Camaro, Nova
The classic 5-slot "Rally wheel" package; extremely popular reproduction wheel, so having ZJ7-style wheels on a car proves nothing about the rest of the build without the SPID.
Mouldings, spoilers, roof panels and exterior trim.
Style Trim Group
Camaro
Bright drip-rail, roof, hood, and belt moldings plus body-colored door handle inserts; a common, inexpensive add-on that restorers often re-create from reproduction molding kits without documentation.
Rear/front spoiler
Camaro
Factory front and/or rear spoilers, commonly seen on Z28/SS Camaros; aftermarket spoilers of the correct shape are widely sold, so mounting-hole and paint-overspray patterns are the usual originality check.
Removable glass roof panels (T-tops)
Camaro
Factory T-top option; a highly visible RPO on the SPID label, but T-top conversions were also done aftermarket, so the SPID is the only reliable originality proof.
Vinyl roof cover
Camaro, Chevelle
Full vinyl top option; correct pattern/grain (e.g., "cross-fire" vs "elk-grain") varies by year and is a common area of restoration mismatch.
Door edge guards
Camaro, Chevelle
Chrome edge-guard trim; among the cheapest and most commonly-added-later dealer accessories, so do not treat it as a rarity indicator.
Body side molding
Chevelle
Was specifically not available with the "Heavy Chevy" YF3 package, a useful cross-check when validating a Heavy Chevy build sheet.
Belt reveal molding
Chevelle
Upper body-side bright molding along the beltline.
Roof drip molding
Camaro, Chevelle
Bright roof-drip-rail trim; part of the larger Z21 Style Trim Group on Camaro.
Exterior ornamentation
Chevelle, Camaro
The code was reused for different trim on different lines - buyers should not assume identical content between a Chevelle and a Camaro build sheet.
Sources differ: macswebs.com describes B94 as "External Ornamentation SS Tailgate" on 1970-71 Chevelle; nastyz28.com describes B94 as "Exterior Ornament (Z28)" on 2nd-gen Camaro. These are two different physical parts sharing the same code on different model lines.
Front bumper guard
Chevelle
Chrome bumper guard option, dropped from the Chevelle order guide after 1970.
Appearance Guard Group
Chevelle, Camaro
Bundled B93 door edge guards, B37 floor mats and D34 vanity mirror; a low-cost "dealer add" group, not a performance/rarity indicator.
Special paint
Chevelle, Camaro
Fleet/special-order paint colors outside the normal color chart, usually ordered for large corporate/government fleets; a genuine ZP3 car in a non-catalog color is a documentation-worthy rarity.
Factory decal and stripe kits.
Sport/Z28 stripe package
Camaro, Chevelle
Used across GM for factory decal/stripe kits, most famously the Z28 hood-and-deck stripes; because reproduction stripe kits are inexpensive and easy to apply, D88 by itself proves little without a matching build sheet.
Seats, trim, consoles and interior groups.
Interior Accent Group
Camaro
Wood-grain accents on cluster/steering wheel plus a glove box light; folded into the Custom Interior (Z87) option in later years, which is why the two codes are frequently confused.
Custom Interior
Camaro
Deluxe seat and door-panel trim, extra cluster lighting, wood-grain accents and a luggage-compartment mat; one of the most-reproduced trim panel sets, so verify against original upholstery codes rather than trim alone.
Strato-bucket seats
Chevelle
Bucket-seat interior option, frequently paired with the D55 console; commonly re-created in restorations using reproduction seat frames and covers.
Color-keyed floor mats
Camaro, Chevelle
Simple option that is trivial to add aftermarket; not useful on its own as an originality indicator.
Front console
Camaro, Chevelle, Nova
Floor console, almost always ordered with bucket seats and a floor-shift transmission; missing console mounting holes under carpet are a common restoration tell.
Special instrumentation (gauge package)
Camaro, Chevelle, Nova
Full gauge cluster (oil, amp/volt, temp) versus base idiot lights; a favorite fake-up since reproduction gauge clusters are readily available.
Deluxe seat belts and front shoulder harness
Chevelle, Camaro, Nova
Upgraded factory belt set; correct buckle/retractor hardware is a common detail missed in seat-belt reproductions.
Rear seat shoulder harness (Deluxe)
Chevelle
Rear-seat belt upgrade added mid/late 1960s as belt regulations tightened.
Shoulder harness (Standard)
Chevelle
Base-level shoulder harness before it became standard equipment.
Air conditioning, glass, wipers, power assists and the rest.
Air conditioning (Deluxe)
Camaro, Chevelle, Nova
Standard factory A/C option; on big-block muscle cars its presence can affect underhood accessory routing that restorers need to reproduce correctly.
Rear window defroster (forced air)
Camaro, Chevelle
Forced-air electric-grid defrosters came later; this earlier RPO used heater-fed ducting.
Soft-Ray tinted glass, all windows
Camaro, Chevelle, Nova
Very common option; tint tone/shade should match factory glass-etch codes if originality is being judged.
Tinted windshield only
Camaro, Chevelle
Cheaper alternative to A01 tinting only the windshield; mutually exclusive with A01 on the build sheet.
Power windows
Camaro, Chevelle
Common comfort option; wiring harness and switch style differ significantly by year, a frequent area of reproduction-part mismatch.
Front seat electric control, 4-way
Chevelle
Power seat option; A46 is the related driver-side-only bucket-seat variant.
Front seat electric control, 4-way (driver-side bucket)
Chevelle
Bucket-seat version of the power seat option, ordered with A51 Strato-bucket seats.
Electric clock
Camaro, Chevelle
Simple dash accessory; part of the ZQ2 Operating Convenience Group on some Camaros.
Speed and cruise control
Camaro, Chevelle, Nova
Early mechanical cruise control system; uncommon enough on base cars that it is worth confirming original hardware is present.
Power door locks
Camaro, Chevelle
Electric door-lock actuators; check for the correct vacuum-vs-electric system for the model year, since GM used both technologies in this era.
Hideaway/special windshield wipers
Chevelle, Camaro
Concealed-wiper system tucked under the cowl panel edge when parked.
Intermittent windshield wipers
Camaro
Variable-interval wiper option, uncommon enough on 1970s Camaros to be worth verifying against the SPID.
Operating Convenience Group
Chevelle, Camaro
A bundled option containing U35 (electric clock), D35 (remote/manual sport mirrors) and C50 (rear defroster); all three sources agree on the exact contents, making this one of the best-documented group codes.
Comfort & Convenience Equipment
Chevelle
Early bundled comfort-option group, discontinued after 1965 in favor of more granular individual RPOs.
Engine block heater
Chevelle
Cold-climate option, mainly seen on Canadian and northern-US-delivered cars.
Radios, speakers and antennas.
AM push-button radio
Camaro, Chevelle
Base factory radio option; correct faceplate/knob style is year-specific and often mismatched in restorations using universal reproduction units.
AM/FM push-button radio
Camaro, Chevelle
Upgraded factory radio; requires the correct dash bezel and dual-speaker wiring to be period-correct.
Auxiliary rear speaker
Camaro, Chevelle
Required U63 or U69 to be ordered; a rear speaker with no matching radio RPO is a red flag.
Windshield antenna
Camaro, Chevelle
Antenna embedded in the windshield rather than a fender-mounted whip; a common give-away when a car has a modern aftermarket fender antenna installed.
Power rear antenna
Chevelle
Short-lived power-retract antenna option, largely replaced by the windshield antenna (U76) later in the run.
Air injection and the state-compliance codes.
California emissions equipment
Camaro, Chevelle
Required for cars sold new in California; often correlates with reduced compression/different carburetion, relevant when verifying a car's claimed original power rating.
California assembly-line emission test
Camaro
Documents that the individual car was emissions-tested on the line for California sale, distinct from the YF5 equipment code.
California emission certification/label
Chevelle, Camaro
Documentation/label code for California emissions compliance; not seen on every Van Nuys-built car even when otherwise California-spec, per period plant records.
High-altitude emissions equipment
Camaro
Required recalibration package for cars sold at elevation; affects correct carburetor jetting/timing specs when verifying originality.
Standard/Federal emissions equipment
Camaro
Baseline 50-state (non-California) federal emissions package.
Air Injection Reactor (AIR) system
Chevelle, Camaro
Early smog-pump emissions system; missing AIR plumbing on a car that should have it is a common "cleaned up" restoration shortcut worth flagging.
Codes that do not sit in one of the groups above.
Positraction (limited-slip differential)
Camaro, Chevelle, Nova
Extremely common option on performance cars; verify against the axle tag/build sheet since Positraction units are easy to swap in during a restoration.
Dual exhaust equipment
Chevelle, Camaro, Nova
Standard on many performance engines and therefore sometimes omitted from the annual options report as a "forced" option rather than an ordered one.
Heavy-duty battery
Camaro, Chevelle, Nova
Common with A/C or big-block engines; battery date codes are a frequent (and easy) restoration-authenticity check.
Trailering axle ratio
Chevelle
Rear axle geared specifically for trailer towing rather than performance; often confused with performance gear codes like ZQ9.
Performance rear axle ratio
Chevelle, Camaro
On Camaro this required G80 Positraction together with a 396/L78 or Z28 engine; a ZQ9 code without a matching high-performance engine RPO on the same build sheet should be questioned.
Canadian equipment/documentation
Chevelle
Administrative code covering the Canadian warranty booklet and related paperwork, not a physical part - relevant when documenting Canadian-market export cars.
Tire pressure chart/decal
Chevelle
Plant-specific documentation code, only seen from the Arlington, Texas assembly plant per both sources; a useful plant-of-origin clue.
Heavy-duty radiator
Camaro, Chevelle
Common with A/C or big-block/high-performance engines; correct core thickness and shroud style are year- and engine-specific.
61-amp Delcotron alternator
Chevelle
Upgraded charging system, typically paired with A/C or other high-current accessories.
55-amp Delcotron alternator
Chevelle
Mid-grade charging-system upgrade offered only in the earliest Chevelle model years.
Codes people search that are not in the table
A row only goes in the table above when two independent references agreed on it. These 23 are codes the hobby asks about that only one reference named, with what that one reference said, so the gap is visible rather than silent.
Four-wheel disc brakes, 1969 Camaro Z28 — one of the rarest configurations of the era and searched constantly for that reason. Only SS396 carried it in what we checked, so it is not in the table.
350 V8, high performance, 245 horsepower, 1973-1974 Camaro Z28 — described as essentially the LT1 with hydraulic lifters. NastyZ28 gives the figure; the only other place naming the same figure was an auction listing, which is not a reference class we count.
396 big-block, 1966-1969 Chevelle SS. It appears only as a bare mention in SS396's Chevelle article, alongside L34, with no displacement or horsepower detail, and nothing else we checked named the code at all.
305 V8, four-barrel, 155 horsepower, 1980-1981 Camaro, required with Z28 for part of that span. NastyZ28 gives that figure. SS396 lists LG4 only generically as a 305 four-barrel across 1978-1987, which does not corroborate the years or the horsepower.
350 V8, 190 horsepower, required with Z28 from 1980 on. Same problem as LG4: the second reference lists the code with no year and no horsepower to check against.
230 inline six, 1965-1966 Chevelle, per the ChevelleStuff year table. No second reference named it.
The hockey-stick side stripe, 1969 — included with SS, optional on non-Z28 cars and not available on the Z28. One reference only.
Sport package: the Rally Sport tape and paint appearance package, 1975-1981 Camaro. One reference only.
Interior Decor and Quiet Sound package, standard with the Type LT, 1973-1981 Camaro. One reference only.
Gymkhana suspension, 1975 Camaro — 15x7 wheels, E60x15 white-letter tyres, special bars, shocks and steering gear, V8 required. One reference only.
Aluminium wheel, 1978-1979 Camaro. One reference only.
The showroom-stock racing package — heavy-duty brakes and suspension and a baffled fuel tank, late 1980s to 2002 Camaro. Outside this table's era as well as short a source.
25th Anniversary Heritage package, 1992 Camaro. Outside this table's era, and one reference only.
Wide paint stripe, side, 1967-1968 Chevelle. One reference only.
The Heavy Chevy package, 1971-1972 Chevelle. One reference only.
Black stripes, D88 colour only, 1972 Chevelle — an internal accounting code rather than something a buyer ticked. One reference only.
F70-14 white stripe tyre option, 1967-1969 Chevelle. One reference only.
Door inner panel moulding, SS — 396 only in 1970, 1970-1972 Chevelle. One reference only.
Custom deluxe seat belts, front and rear, 1966-1972 Chevelle. One reference only.
Deluxe shoulder harness, 1966-1972 Chevelle. One reference only.
Outside mirror, remote control, 1967-1972 Chevelle. One reference only.
AM/FM stereo equipment, 1968-1972 Chevelle. One reference only.
Rally wheels, from a truck-line list. Only the cross-division source named it, and that source is not model-specific enough to stand alone.
Where the references disagree
Printed rather than resolved. Picking a winner quietly is how a wrong number gets into a record and stays there for twenty years.
A rear axle ratio code, and the two references print two different ratios for it. ChevelleStuff's Chevelle year table reads 3.70:1, offered 1965-1966 and 1968. West Coast Differentials' GM-wide table reads 3.62:1. Those are flatly different gears, so there is no row — count the teeth or read the tag on the housing.
There is a row for L78 and both references agree it is the 396 at 375 horsepower. They disagree on which Camaro years it applied to: SS396 reads 1967-1969, NastyZ28 reads 1970, SS only. The row carries both.
What this does not tell you
Whether the car was actually built that way. An RPO code is what somebody ordered, and a code list is a dictionary, not a title search. The document the code is printed on is the evidence; this only tells you what the code means.
Whether the document itself is real. Build sheets and SPID labels are reproduced and sold, and a car wearing the right codes is not the same as a car that left the plant with them. Where a code is commonly faked the row says so.
The paint, the interior trim, the plant and the build date. Those are on the cowl tag, which is a different plate carrying different codes, and the cowl tag decoder reads them.
Casting numbers. The number on your block, head or intake is cast into the iron and is not an RPO code. Those have their own lookups.
Every code GM ever issued. GM issued thousands across every division and every year, and reused plenty of them. This table is the Chevrolet Camaro, Chevelle, Nova and full-size codes that two references agreed on.
Corvette codes. The per-year Corvette references are behind a paywall, so no Corvette-only code could be checked against a second source. Rather than guess, they are out.
- https://www.nastyz28.com/faq/rpo-list.html
The Second Generation Camaro Owners Group RPO glossary — the most complete per-code Camaro list on the open web, and the second-generation reference most of the hobby quotes.
- https://www.ss396.com/cars/camaro-rpo-code-breakdown/
SS396 Camaro RPO breakdown by generation, with a quick-reference table of years and horsepower for the engine codes.
- https://www.ss396.com/cars/1964-1972-chevelle-rpo-codes/
SS396 Chevelle RPO breakdown by category: body and trim, chassis, brakes, steering, wheels, powertrain and the Z-series packages.
- https://www.ss396.com/cars/chevy-ii-nova-rpo-code-breakdown/
SS396 Chevy II and Nova RPO breakdown, the Nova-side source on engine, transmission, axle and package codes.
- https://chevellestuff.net/qd/rpo1.htm
ChevelleStuff's Chevelle RPO-by-year table, A through M, with per-year availability footnotes. The Chevelle-side source on engines, transmissions and axle ratios.
- https://macswebs.com/chevyworld/decode/rpo/rpo1.html
ChevyWorld's 1964-1972 Chevelle RPO table, A through M. Same operator as ChevelleStuff, so it was not counted as an independent second source where ChevelleStuff already carried the code.
- https://macswebs.com/chevyworld/decode/rpo/rpo2.html
ChevyWorld's 1964-1972 Chevelle RPO table, N through Z, plus the trim and colour combination codes.
- https://www.camaros.org/trans.shtml
Camaro Research Group on transmissions: the M13 and MC1 heavy-duty three-speeds, the M20, M21 and M22 four-speeds with gearsets, and where M11 floor shift applied.
- https://www.camaros.org/copo.shtml
Camaro Research Group's COPO 9560 and 9561 report — the L72 iron 427 and the aluminium ZL1, with the horsepower GM filed and the horsepower they made.
- https://macswebs.com/chevyworld/chevelle/ls5_prod_numbers.html
ChevyWorld's LS5 and LS6 production numbers by year and model line, used for how the Z15 SS454 package and the two 454s related.
- https://differentials.com/gm-axle-ratio-identification-codes/
West Coast Differentials' GM-wide axle ratio code table, used only to corroborate the numeric ratio of an axle code a Chevelle or Camaro source already carried.
- https://heacockclassic.com/articles/the-best-muscle-car-1970-ls6-chevelle/
Heacock Classic on the 1970 LS6 Chevelle, the second source on the 450 horsepower rating and its relationship to RPO Z15.
- https://www.cjponyparts.com/resources/vintage-chevy-rpo-codes
A cross-division 1967-1986 GM RPO list, weighted to the truck lines. Used only to corroborate the description of a code that was shared GM-wide.
The codes say what was ordered. For what is actually bolted to the car, the block casting number lookup and the cylinder head casting number lookup read the numbers cast into the iron, and the Camaro cowl tag decoder reads paint, interior trim, plant and build date. Hold a code we do not, or spot a row we have wrong? Write to buildbook@nanocorp.app and it gets checked with the source named.