Covers any US-market VIN built 1981–present (standard NHTSA 17-character format). Free, pulled live from NHTSA's public vPIC database — this includes newer Challengers and Corvettes, not just classics.
Pre-1981 VINs aren't in any federal database — there's no free universal lookup for them. Pick the make/model above, then this breaks the VIN down positionally using published manufacturer reference charts. Some fields (car line, body style on certain models) shifted year to year, so cross-check those against your fender/door tag before treating them as final.
Fender tag code lookup
Type in what's stamped on your fender (build) tag — top paint code and trim code are the two most people have on hand. This is a starter reference, not exhaustive, and paint-code accuracy especially benefits from cross-checking (see the registry link below).
Reference: common 1970–71 "High Impact" paint codes
How to read a trim code
Mopar trim codes generally break into three parts: a level letter (P = Premium, M/H = Medium/High, etc.), a seat-type digit (bench vs. bucket), and one or two color letters. For example, a real 1970 fender tag showing P6XW reads as Premium, vinyl bucket seats, black & white two-tone.
| X | Black |
| W | White |
| B | Blue |
This color-letter list is intentionally short — it's only what's cleanly confirmed across multiple sources so far. The seat-type digit specifically (bench vs. bucket) has some inconsistency between references I found, so I haven't built it into a composed lookup table the way paint codes are — for that piece specifically, cross-check against a dedicated Mopar fender tag decoder or a year-specific chart.
Beyond the VIN: build/broadcast sheets
On GM and Mopar cars from this era, the factory paperwork that followed the car down the line — the build sheet or broadcast sheet — was never meant to survive; it was just work-order paper for line workers. When one does survive, it's often stronger evidence than a VIN/cowl-tag decode alone, especially for confirming genuinely optioned cars (GTO, 442, GS, SS, Hemi, etc.) where the VIN series code can be ambiguous or shared with lesser trims.
Where they're commonly found: loose behind the rear seat back, tucked under the seat springs or seat cushion, on top of the gas tank, under carpet or door panels, or stuck to the underside of the trunk mat. Worth checking before assuming a car's a "clone" based on a VIN mismatch alone.
Caveats to hold onto: most cars never had a build sheet or it was tossed decades ago, so absence isn't proof of anything either way. A sheet can also get mismatched between cars on the same line (workers occasionally grabbed the wrong copy). Treat a found build sheet as strong supporting evidence, not a substitute for VIN + cowl tag + physical inspection.
Is the engine actually original to this car?
This is the question the VIN and fender tag can't answer — they tell you what the car was born with, not what's between the fenders today. Engines get swapped, and unless someone tells you, there's often no obvious sign. These three numbers, read together, are how you check.
| 1. Casting number | Raised (not stamped) into the block itself — usually the driver's side, or on the bellhousing flange at the rear of the block on big-blocks. Tells you the block family/design (e.g. "this is a 440 RB block"), not which specific car it came from. |
| 2. Stamped ID pad | A separate, stamped (not cast) code — on most GM/Mopar V8s it's on a machined pad at the front, passenger side, just below the head. This is the one that actually ties to a specific car: it typically ends in digits matching the car's own VIN sequence. This is the one most people don't know to look for — if it doesn't match the car's VIN, the engine isn't original to that car, no matter how correct the casting number looks. |
| 3. Casting date code | Cast into the block near the casting number — a date the block was poured. It has to predate the car's build date (found on the fender tag/data plate). A block cast after the car was built obviously isn't original to it. |
Reading these correctly takes all three together — a correct casting number with a non-matching stamped pad is a swapped (but often period-correct) engine, not a numbers-matching one.
Casting number starter reference
This covers a handful of the most iconic muscle-car blocks — it is nowhere near a complete casting-number database (those run into the thousands per engine family). Type a number to check it against what's here; a miss just means it's not in this starter set yet, not that it's wrong.
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