There are 5 matching parts on the M20: Frame, slide, action block, barrel, bushing. Very hard to find them all matching. As previously stated, most are Vietnam bringbacks. I don't think very many were ever imported. Almost all of them lack import marks and safeties.
From another board
http://www.gunsnet.net/forums/showthread.php?t=104195:
"Three original military versions (Chinese Tokarevs):
1) T51: Russian parts assembled in Chinese arsenals in Manchuria. Production started in 1951.
2) T54: Domestic production; type-designated in 1954. There is no difference between T51 and T54 except marking. T54 has three Chinese characters on top of the slide (Five-Four-Type), while T51 has three characters on the left rare side of the frame (Five-One-Type)
3) M20: the most interesting variation. They were identical to T54, but were marked M20 on tope of the slide. These were made for supplying various communist insurgencies, national liberation fronts, and Viet Nam troops. It has no Chinese markings, so the the source of supplier can be denied when the weapons are cought in embarrassed situations.
There are three Mxx weapons: M20: Type 54 Tokarev pistol; M21: Type 56 semi-auto rifle (SKS), and M22 (Type 56 assualt rifles, aka AK47)."
Jack