well in theory it could be 89 but likely in the 80 to 87 era probably..since most new rifles would be still in homeland armorys and weapons would be reissiued in country..lots of AKMs as well were used.
It's a good question. With the exception of early batches earmarked for special use or training purposes, most all of the new production AK-74 rifles were sent to frontline troops and thus directly into the conflict. In the first few years of the war, great numbers of standard ground troops were still equipped with the AKM, but by the mid-80's most of these had been replaced as more and more AK-74's were rushed into theater. This was made possible by surge production of the late 70's-early 80's (when production reached nearly a million rifles a year). This greatly increased the number of available AK-74 rifles, and thus accelerated the rate of transition. After ten years of war, almost no Soviet troops were still issued with AKM, except for a few specialty types. By that time, if freshly equipped (or manned) units were sent into Afghanistan near the end of the war, depending on the type of unit it was the odds are very good that at least some of their personnel were carrying new condition rifles with fairly contemporary dates. That most definitely included 1987's (found left in A-Stan) and probably some 1988's, but I'm guessing 1989's were not very likely.