victorsam> I have a 11A LOS built Coupe no where near as well optioned as yours, but it has the original drivetrain, including the 657 cast block. Mine was a 210 hp. 2 bbl. with a Powerglide trans. behind it, build date on mine is J 17 6. Much closer to build date of car, I agree with what someone else stated, that by this time the dates should be ccloser together. I think someone else posted, you will not find a partial VIN.# unless it was originally a HP engine.