What should a 70 Chevelle rear quarter fender marking stamp look like? See photo...it this real or reproduction?

I can still see the factory spot welds in the corner where the quarter meets the filler. That would probably be a factory stamp. Probably says something like 134 1 3 or similar...

That looks pretty original. I haven't seen nor heard of someone trying to restamp that yet but I suppose it's not impossible.