I thought all 64 1/2 thru 73 Mustang VINs started with the year code (3 for 73, 1 for 71, etc). I have found an advertised 1973 Mach 1 that lists a VIN that starts with "A". I asked the seller about this and was told that it was a "late 1973, after Ford decided not to build any more Mach 1's". There is also an "extra" letter in the code, after the engine code. I can't find any reference anywhere that says Ford ever issued VINs in 1973 that started with an "A". Can anyone confirm this?