Quote:
Originally Posted by 05GTO
That casting number was used for the 389 in 65 and 66, the letter code YF is for a 1965 389 with 325 hp, Auto 4bbl and AC. More than likely the engine was for a b-body full size pontiac. The GTO's only offer the 389 with 335 and 360 hp.
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1965 GTO option 389 codes will be WT or WS for manual 335 or 360 hp
YS or YR for Automatics
It is a replacement block. Is the casting date at least approximate to your build date? I've not done it myself, but if you have a numbers matching motor that is plausible to your car's build date, there might be some value in looking into having the code on the replacement block restamped to one of the above codes. I know a lot of Vette guys that have gone that route.
Mike
