I suggest you contact GM's Vintage Vehicle Services www.vintagevehicleservices.com For a small fee they will send you the line sheet and what they have matching your vehicles vin, that should help clear things up for you.
I have seen cars in the past that had the serial number plate changed. Not necessarily because the car was stolen, but to avoid paying transfer and license fees. Times were tough in the sixties for some families. The plate should be held on by a type of hollow rivet, not screwed on. I have included a picture showing the type of rivets. Sometimes the rivets may have a sealer dabbed on to fill in the hole in the centre.
Paul
-- Edited by Prefectca on Saturday 7th of October 2023 09:02:37 AM