heck, I'll give this one a shot...Didn't the 64 stand have chrome trim on the hood, and the 65 didn't?? And as far as the bonus, another guess, they changed from Gen. to Alternator...Once again a guess..I think I remember ready that they changed that over very very early on in the 'stangs life....
If I am far off, then don't laugh too hard..lol
I just saw that the difference was with the seat, so I am clueless on the bonus...I'll guess that they added the chrome trim to the back edges of the seat..??