Sorry for cutting and pasting, but I assume the person asking on facebook is yourself.
There are two (or more depending on your argument) versions of the short 7.62x39 version.
The version with underfolding stock, OR side folding stock is from the early 90s to today. Same basic piece as the "Draco" pistols imported into the US today.
The earlier version with "crutch" stock (or no stock) is different, and supposedly uses a slightly shorter gas system/piston.
Any other details about the early version seem to hard to find. There is one on display at the Military museum in Bucharest, but they will NOT allow me (as an author) to take items out of the display case for photography, and they have nothing in "the basement" like Western Military museums.
I do have great images of the later 1990s version in my book "the AK47 catalog volume 9".
If I were doing a build, I would use a late "domestic" 1980s parts kit as a base.
1- Your guess is as good as mine. These don't seem to have been made in great numbers, otherwise they were be more common on the export market.
2-It is different. I remember reading years ago that it was actually slightly shorter.
3- Domestic markings.
4- Same as a period md.63, which is another reason to start with a similar period kit.