I'm inclined to say they're aftermarket. They look plated to me. The groove appears differently also. I will say though, the only ones I've seen came off my jeep and the older Bantam trailer that I have. I'm sure others with more experience can correct me if I'm wrong but a vehicle this old should not have any hardware on it that's metric. Therefore, NOS (New Old Stock) can't be metric. I've read the auto industry here switched in the '70's. Prior to that, the hardware should be SAE (or inch base). Replacement parts can be metric (I've gotten a few).
So if anyone knows I'm wrong, correct my errors!
They still should work if they fit.
