I am in the process of buying a 66 GT to rebuild. The sellertold me it has a numbers matching engine, trans, and rear end. I've seen somewhere that for 64 - 66 cars, Ford did not keep records like that. Best you can do is determine if th drivetrain components and the car were manufactured within the same 90 day window. Can anyone help clear this issue up for me ? How do you check this isssue ?