Great information here.
A question for you is if the cars have sequential serial numbers and you don't have a build sheet for either but you have a fender tag for both, can you determine if they were indeed built back to back?
The cars in question are both '69 Coronets, one a 2 door and one a 4 door in different colors, options, etc.
I do own both cars and sadly they are just parts cars.
Interesting nonetheless................
