Hi, I am looking at a 68 firebird and the guy says that it is a 350-HO but I want to make sure. The vin # is 223678L105840, the numbers on the front of the engine are 00379831 ym and below that # are 25X108951 I don,t know the casting #yet. How can I tell if this engine came with the car and is it an HO. Thanks for any info. Harold
Best way to check the car is correct to the vin is order a PHS report on the car. I did it on mine and was very happy I did. Gives you every option the car was built with.
What you're saying would be right for a 1968 motor. But what you're telling the guy is something that ain't right about the motor that's in the car he's looking at. It's not the original motor. It's not a 350 HO. It's not even a 350. You won't need the PHS docs to confirm that.
Did you notice he posted the partial VIN number? It's from 1975, not 1968. The 1975 YM is a 400. Its NOT a 1968 YM 350 HO. The casting number will be 481988 (early), not 500557 (and not 9790079).
Saying it was a Bonneville motor was just a guess. As it turns out, it was a bad guess since it came from the old Kansas City plant ("X" in the VIN). 1975 production there was A body cars, so that makes it a LeMans or a Grand Prix engine - not a Bonneville engine (as I assumed originally).
Didnt check for other years, but just did. There is a ym in 75. 400 used in b-bodies.
Guess i should of been clear'r. Not say'n its a 68 350 HO. The last 2 eng digits(29) vs (31) is the important note. As well as # on r/r top of blk. 481988(up to 74-strong ones) vs 500557(75 and up-weak ones).
FWIW, the 6th digit of the vin is the yr that the car was built.