Apparently the Russians stopped production in 1955 but I remember reading once some may have still been produced 'till 1957. Personally I have never seen on built after 1955. The North Koreans if I remember correctly never started production 'till 1968 and that would be the one to try to find. I think the NK's made them for about 20 years so there might be a 1988 one out there.

I am not sure about when other countries stopped their manufacture.