The project for the weekend is replacing the valve seals on my son's 1988 GTA. Now that the block stampings are exposed, we thought we would check to see if this thing still has the original engine:

VIN # of the car is 1G2FW21F7JL233546.

Block stamping is 2JL233546.

Close, but the 9th digit in the VIN and all body stickers is "7", and the stamping on the block is a "2". I'm confident that this is the original engine because the last 8 digits correspond. My assumtion is that the operator of the stamping machine at the factory loaded in the wrong tool.

If anyone has a better expanation, please post.

 

My brother's 91 (Camaro) VIN check digit is a 7 but the block stamping at that position is a 1 (otherwise the block stamping is same as VIN).

 

I thought I would check on Corvette Forum since those guys are into documentation, and the 80's Vette's also used TPI. Got a sensible explanation for the block stampings:

First digit of the VIN stamping on block designates the GM division - 1=Chevrolet, 2=Pontiac. The remainder of the stamping will match the last 8 digits of the VIN of the car.

This explanation fits with both my son's car, and Time2Fly's brother's car.