I just watched the WCCC video and they said the 91 describes it as a “Cougar Hardtop”. What should the VIN call out if it was an XR7? Also, do you know what the 6 stands for? Note: If I watched it correctly, the last 5 numbers are the serial number.
617492: 117492 issued VIN. Ford Numbers begin with 100001 for Mustang and 500001 for Cougar at each plant. In 67 Cougar was only built at Dearborn. The serial number gives us clues about production date but keep in mind this number is not the sequential production number. Most likely this Cougar was built in May of 1967 according to The Mustang and Cougar Tag Book by Kevin Marti.
The origin in Lake Havasu Arizona is good. Depending on when you went to high school and who you sold it to the car may still exist. If the car was sold in Detroit or Illinois it may be rusted away now. The 91 in the VIN means your car was a standard coupe. If it was an XR-7 it would have a 93. The A code means that your car had the 225 HP 289 which is better than the base engine which would have been code C for the 289-2V which made 200 horsepower.