Discrepancies happen with VINs sometimes. Keep in mind that in the era when your car was built, a lot of auto workers were, uh - 'a bit under the weather' (or something similar). You should verify all the VINs on your car; the one on the door, the one riveted to the body at the left windshield and the title. A further check can be made with Kevin Marti at
http://www.martiauto.com/ Kevin bought the Ford assembly line database for 1967 thru 1973 Fords and can give you a lot of information about your car - for a price of course, around $30.00.
Jim