Where the VIN is on a full-size Chevy or GMC
- Windscreen. A metal plate on the dash, driver’s side, readable from outside. Standard from 1968 on.
- Driver’s door jamb. On the certification label with the tyre pressures and the GVWR.
- Registration and insurance. Quickest source if the truck is not in front of you.
- Frame rail. Stamped on the frame, usually behind a front wheel. Often the only one left on an older truck.
What a VIN can and cannot tell you
It does tell you
- Model year, make, model and series
- Body and cab configuration
- Drive type — 2WD or 4WD
- Engine family and displacement, and on most trucks from 2003 the engine RPO
- GVWR class and the assembly plant
It does not tell you
- Your option codes. A VIN does not carry the RPO list. Only the SPID label in your glove box does.
- Axle ratio, transfer case or whether it has a locker
- Paint code, interior trim or bed length
- Anything that has been changed since it left the plant
- Service history, accidents or title status
This is the honest boundary between the two tools. The VIN establishes what the truck is. The RPO decoder reads how it was optioned, off the glove box label.
Which generation your VIN points to
These are the platforms this site covers. A Malibu, a Colorado, an Equinox or a Ford will still decode — you get the federal record and nothing else, because none of them are on one of these platforms and sending you to a hub for them would be wrong.
| Generation | Model years | Hub |
|---|---|---|
| Classic (1947-1972) | 1947–1972 | Open |
| Squarebody | 1973–1987 | Open |
| GMT400 | 1988–2000 | Open |
| GMT800 | 1999–2007 | Open |
| GMT900 | 2007–2013 | Open |
| K2XX | 2014–2018 | Open |
| T1XX | 2019–present | Open |
1999–2000 and 2007 each had two platforms in production at once. A VIN cannot separate them, so both are shown when your truck lands in one of those years.
The 17-character standard, and the 1981 line
The 17-character VIN became mandatory for trucks manufactured on or after 1 September 1980 — model year 1981. Everything built before that used shorter, division-specific schemes. The government record starts at the standard, so there is simply nothing on file for a 1979 Squarebody — which is why we built our own tables for those years.
For 1973–1980 GM trucks we decode the 13-character VIN from our own reference tables. Those tables are community-sourced, not factory documented: the GM Heritage Center information kits for those years are photographic scans with no machine-readable text, and GM published no dealer VIN card for a 1973–1980 truck. We show every meaning with its sourcing, and where our sources contradict each other — the engine letter in 1977, 1979 and 1980 — we show both readings rather than pick one.
1947–1972 is out of scope. Those VINs are shorter again and we hold no sourced tables for them. The Classic hub is the better starting point.
Where this comes from
- Generation, platform and the 1973–1980 tables are FullSizeChevy’s own work — the mapping from a model year to the platform you actually need, and the pre-1981 reference tables the federal database does not cover at all.
- Factory build data for 1981 and newer comes from the federal vehicle database, queried live and cached.
Found something wrong, or hold a factory document that would settle one of the 1973–1980 conflicts? Tell us on the forum. A page from a GM service manual or a Heritage kit would let us promote those tables out of tier 2, and that is a real contribution.
Redact your VIN before posting any photo of a door jamb or a title.
This describes how a truck was built at the factory, not how it is configured today. Verify against the vehicle before ordering parts or making repairs. FullSizeChevy.com is not affiliated with, endorsed by, or sponsored by General Motors; Chevrolet, GMC, Silverado and Sierra are trademarks of General Motors LLC, used here only to identify applicable vehicles. Terms