Block VIN and other codes and numbers - 1974 or 1975.

[jcdkool]

I have a 400 cid(6.6L 4bbl NA Turbo400) in my 1973 Grand Prix J with a block VIN code 25A127360, engine block casting number 481988, date code A215, engine block code YT, motor unit number 0234326. There is a 75 and 2 D<)N next to distributor pad. Most of this information seem to indicate this engine was original to a 1975 model but the block casting code refer to a 1974 model. Can someone decode and determine correct year and which model this engine was original to? Are there other codes or numbers on engine that will further identify the original year and model?

[idrivejunk]

Thats an early (cast on January 25th) 1975 4-barrel 400 with automatic trans. Last of the good ones. The last six digits of your block code are sequential and would match it to a car if it had the same last six. Original head castings could provide clues but as far as what kind of car it came in, I would guess Firebird. Can't nail that down without records but its no matter if you're not trying to prove it belongs to a certain body. All the answers are at the top page of a google search, as you might have found.

http://www.pontiacpower.net/castnum01.html

Beginning in mid 1975, blocks were cast with less material in a couple areas and they changed the crankshaft flange. This limits performance potential somewhat. I have a used up 988 block and also one of the later ones and you can tell side by side. Block casting changes applied to 455s also.

[jcdkool]

Is there any way to determine which Pontiac models were assembled at Lakewood(Atlanta) in early 1975?

[idrivejunk]

That I do not know. I do know Atlanta made lots of Grand Prixs in lots of years. My 72 was built there. I had a 75 GP with a 400 4 barrel automatic but it was in the early 90s and don't remember which plant.