I guess the question would be, where the numbers on your plates a number that is considered to be commercial now, or then? If the plates were passenger then, and the current number sequence would make it a commercial number, they should be usable for your car. If the plates were commercial plates (truck/pick-up plates) back in the day, they should only be usable on trucks.

I'd bet the plates you had were passenger plates for the time. The wording says the plate has to be correct for the vintage. As for the plate numbers not currently being used, that was what I meant about the plates being cleared.