How to Tell a Real Stage 1 From a Story

Start with the body code, because it rules out more cars than anything else. A 1970 Stage 1 had to begin life as a GS 455, which means a VIN starting 44637 for the hardtop or 44667 for the convertible, with the year and the Flint assembly code following. If the VIN says Skylark, the conversation is over no matter what is bolted to the engine.

Here is the part that catches people. The VIN confirms a GS 455. It does not confirm Stage 1, because Stage 1 was an option code rather than a separate model, and option codes do not live in the VIN. Buick built roughly 2,865 Stage 1 coupes and 232 Stage 1 convertibles for 1970, so the real ones are out there in reasonable numbers. So are the tribute cars wearing decals.

What Stage 1 Actually Added

The option was a genuine hardware package, which is good news for a buyer with a flashlight. Stage 1 heads used larger valves, 2.125 inches on the intake side against the standard 2.00, and 1.75 on the exhaust against 1.625. Add dual valve springs, a higher-lift camshaft, a rejetted carburetor, a recurved distributor, a high-volume fuel pump, a larger oil pickup, a seven-blade heavy-duty fan and a posi rear. Stage 1 cars wore chrome valve covers. Cars ordered with the automatic got a specific TH400 carrying the transmission code BB. An original transmission also carries a serial number that reads as a 4 followed by the last eight digits of the VIN, which is a fast way to confirm the drivetrain has stayed together.

The VIN tells you it is a GS 455. Only the paperwork and the hardware tell you it is a Stage 1.

Then go looking for paper. The Production Order Body sheet usually hides on top of the fuel tank under the sound deadener, or in the rear seat springs, and the Flint build sheet often turns up under the dash or against the driver side pillar. Either one settles the argument in a way that a fresh set of stripes never will. The Stage 1 Registry keeps the definitive identification notes on all of this and is worth reading in full before you hand anyone a deposit.