GMC Division Index — Light Trucks (1960–1982)
GMC light trucks of this era are badge-engineered siblings of the Chevrolet C/K family and share the corporate RPO system and almost the entire option book. Use ../chevrolet/trucks.md as the master code reference for any 1963–82 GMC C/K 15–35 pickup, Jimmy, or Suburban; this index documents what is different on the GMC side.
Model mapping:
| GMC | Chevrolet equivalent | Years |
|---|---|---|
| C/K 1000–3500 ("New Design" → Action Line) | C/K 10–30 | 1960–66 (1000/1500/2500/3500), 1967+ (1500/2500/3500, badged 15/25/35) |
| Jimmy (full-size) | K5 Blazer | 1970–82 (K5 Blazer from 1969) |
| Suburban / Carryall | Suburban | 1960–82 |
| Sprint | El Camino (Chevelle-based) | 1971–77 — codes in ../chevrolet/chevelle.md |
| Caballero | El Camino (Malibu-based) | 1978–82 — codes in ../chevrolet/chevelle.md |
What is GMC-specific
- Trim/appearance package names. The same RPO number buys a different badge on a GMC (see master table below). This is the main thing a decoder needs to translate.
- 1960s drivetrains. Through the 1960s GMC fitted its own engine family — notably the 305/351/401 cid GMC V6 (and Toro-Flow diesels) — instead of Chevrolet sixes, plus GMC-specific option numbering on early trucks. Coverage gap: no machine-readable GMC option-code list for 1960–66 was located online; GMC order guides / GM Heritage info kits (image scans) are the lead for a future pass.
- Limited editions (Gentleman Jim, Beau James, Indy 500 Official Truck packages, mid-1970s): sold as GMC-only appearance packages; RPO-level documentation not located online — gap.
Master trim RPO table (GMC names)
| Code | Description | Years | Models/Notes | Confidence |
|---|---|---|---|---|
| Z17 | Sierra Grande trim | 1967–72 | GMC Action Line pickups/Suburban; Chevrolet had no Z17 (used Z84/YE9 ladder) | single-source |
| — | Deluxe (base) / Custom / Super Custom trim ladder | 1967–71 | Pre-1972 GMC ladder; order codes for Custom/Super Custom not located | confirmed (names) / gap (codes) |
| — | Custom / Super Custom / Sierra / Sierra Grande ladder | 1972 | Sierra & Sierra Grande introduced as Cheyenne / Cheyenne Super counterparts | confirmed (names) |
| Z62 | Super Custom (1973–74) → Sierra Grande (1975–81) → High Sierra (1982) | 1973–82 | = Chevy Custom Deluxe → Scottsdale | confirmed |
| Z84 | Sierra (1973–74) → High Sierra (1975–81) | 1973–81 | = Chevy Cheyenne; discontinued after 1981 | confirmed |
| YE9 | Sierra Grande (1973–74) → Sierra Classic (1975–82) | 1973–82 | = Chevy Cheyenne Super → Silverado | confirmed |
| Z77 | Street Coupe package | 1976–81 | = Chevy Sport; shortbed 1/2-ton, graphics + N67 rally wheels + V22 + BC2 | confirmed |
| YG8 | Royal Sierra package | mid-1970s–82 | = Chevy Bonanza; year-end value group | confirmed |
| — (base) | Custom (1973–74) → Sierra (1975–82) | 1973–82 | Base trim, no RPO | confirmed |
Jimmy top options mirror the K5 Blazer: CB8 removable top, Z58 removable top (white), Z59 removable top (black) — 1970–75 full removable top, steel half-cab with removable half-top from 1976. See the Blazer rows in the Chevrolet trucks doc.
Shared-code quick reference
All of the following work identically on GMC trucks (full detail and confidence labels in ../chevrolet/trucks.md):
- Engines (1973–82): LD4/LE3 250 I6, L25 292 I6, LS9/LT9 350, LE9/LF3/LG9 305, LE8 454, LF9 350 diesel, LH6/LL4 6.2L diesel. (During 1967–72 the GMC 305 V6 was phased out of light-duty models in favor of shared Chevrolet gas engines; exact changeover years per series not verified — gap.)
- Transmissions: M20/MM7 manuals; M38/M49/MV4/M40 Hydra-Matics; MD8/MX0 700R4 (1982).
- Axles/4WD: G80 locking differential, GT4/GT5/GU4/GU6/HC4 etc. ratios, NY1/NY7 skid plates and shields, F76 locking hubs (67–72).
- Appearance/convenience: ZY1–ZY5 paint schemes, YG1/YG3 molding packages, V22 deluxe front appearance, C60 air conditioning, ZQ2 power window/lock group, Z81 Camper Special, Z62/Z84/YE9 trim levels (GMC names above), Z53 gauges, N67 rally wheels, R05 dual rear wheels.
1963–66 shared RPOs (from Chevrolet factory kits — GMC applicability inferred)
An OCR mining pass over the GM Heritage Chevrolet truck data books (T1) rebuilt the 1963–66 code list in ../chevrolet/trucks.md. Those kits are Chevrolet-branded, so GMC applicability is inferred, not factory- confirmed for GMC specifically — but because GMC shared the corporate RPO system and nearly the whole chassis/body option book, the following 1963–66 Chevrolet codes almost certainly carried the same meaning on GMC C/K 1000–3500:
- Chassis/brakes/suspension: F49 HD front axle, F51 HD shocks, F59 front stabilizer, F60 heavy front springs, F76 front locking hubs (K-series), G50 HD rear springs, G60 aux rear springs, G80 Positraction, G86 No-Spin, H01/H04/H05 axle ratios, J50/J70 vacuum power brakes.
- Electrical/cooling/chassis: K24 PCV, K28 fuel filter, K46 HD air cleaner, K66 transistorized ignition, K67 HD starter, K76/K77/K79/K81 Delcotron generators, N01/N02 fuel tanks, V01 HD radiator, V04 radiator shutters, V05 HD cooling, T60 HD battery.
- Body/interior/appearance: A09 Soft-Ray windshield glass, A11 Soft-Ray all-windows glass, A10 full-view rear window, B98 side molding, D29/D30/D32 mirrors, N33 Sports-Styled wheel, N34 Comfortilt, N40 power steering, P01/P02 wheel covers, P10/P13 spare carriers, U16 tach, U60/U63/U69 radios, V31/V35/V37/V38/V43 bumpers, V62 jack, V74/V75 lamps, V76 tow hooks, Z52 foam seat, Z53 gauges.
Do NOT assume the engine RPOs carry over: the Chevrolet 1963–66 engine codes (L21 194, L26 230, L25 292 sixes; L30 327 / L32 283 V8s) are Chevrolet-specific. Through the 1960s GMC fitted its own 305/351/ 401 V6 family, so GMC used different engine option codes for these years (still an unfilled gap — see item 2 above). Likewise the 1960–62 numeric option codes documented in the Chevrolet doc were Chevrolet's numbering; GMC had its own early numbering.
Sources
- 73-87chevytrucks.com trim level guide (Chevy/GMC name mapping per code and year): http://www.73-87.com/7387info/7387trimlev.htm
- GM Authority — GMC Sierra Grande, High Sierra, Sierra Classic history (trim/RPO history 1967–87): https://gmauthority.com/blog/2025/10/gmc-sierra-grande-high-sierra-and-sierra-classic-history-alley/
- Out In The Shop — 67-72 Chevy/GMC RPO codes (incl. Z17 Sierra Grande): http://outintheshop.com/options.html
- GM RPO codes & descriptions master list (PDF; confirms Z77 "Chevy Sport or GMC Street Coupe", YG8 "Bonanza/Royal Sierra package", Z84 "Cheyenne, High Sierra"): https://rparts-sites.s3.amazonaws.com/dec399b0838336997484042ed2af1004/design/rpoCodes.pdf
- Halderman GM RPO code list (PDF): https://jameshalderman.com/wp-content/uploads/2019/04/RPO_Codes.pdf
- 73-87chevytrucks.com RPO lists: http://www.73-87.com/7387info/7387rpo1.htm , http://www.73-87.com/7387info/7387rpo2.htm
- Wikipedia — Chevrolet C/K (second generation) (GMC trim ladder 1967–72): https://en.wikipedia.org/wiki/Chevrolet_C/K_(second_generation)
Known gaps: GMC 1960–66 option codes (own numbering + V6 engine options); Custom/Super Custom order codes 1967–71; Gentleman Jim / Beau James package contents; Sprint/Caballero-specific GMC badging codes (body/trim otherwise per Chevelle/El Camino doc).