Vin, Body Tag, and Engine Code Information

Q: Vin, Body Tag, and Engine Code Information

Running the vin number and body tag number on oakmediacreations firebird page the production numbers of the vehicle didn’t match one another plus what do the codes on the engine stand for:

Block Casting numbers on R/F of engine (only numbers I can see)
GM4

Stamped numbers on the right front of engine block
508743
YJ

A: This is correct, these two numbers found on the body tag and the VIN will not match. The numbers on the VIN represent the Sequential Production Number. The numbers on the Body Tag represent the Unit Number or consecutive build number. The last tells in sequence when the car came off the assembly line. Again, the body tag number will not match the actual sequential VIN number.

Block Casting numbers on R/F of engine (only numbers I can see) GM4
I do not know what these represented on the block.

Stamped numbers on the right front of engine block
508743 = Motor Unit Number
YJ = 8 cyl, 326 cid, 250 hp, 9.2:1 comp. ratio, 2 bc carb, auto trans.

Sources: Firebird Red Book, Catalog of Firebird ID Numbers 1967-93, Pontiac Historic Services, Year One Catalog

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