There was a shot of one of these on NRA Guns and Gold, I think that's the name of the show last week
A guy had a complete rifle, wasn't cheap.
You may be able to find the show online, it was on sportman channel
Mike
It COULD be uncommon. NODAK Spud, the main maker of AK receivers stateside, makes an upper just like that. I think if it's an original, it would be Vietnam era? I could be wrong on that part.