Well, I'm stumped. After looking at pictures for an hour I've got nothing. They're not from a '66 Cadillac. The Cadillac bumper is much more defined than these and doesn't have the bolts coming through the front like these do. I can tell you that there is one rear and two front bumpers (duh) and I'm pretty sure they are Buick. I looked at a lot from 1967-1971 with a lot of them being close but not exact. Maybe I didn't look hard enough. They are definitely pre-1972 though. After that, the government mandated bumpers to withstand a 5-mph impact which meant almost all bumpers had those big ugly bumper guards or a rubber strip running around them. Are there any part numbers on them? Or the mounts? That could help. I'll keep looking...maybe I'll find a match. These are in good shape though. You should make some money on them!