Well, the cover, and let’s assume it was attached to an NK SKS (not a Chinese or Russian SKS, as in your pics
) ended up in Afghanistan. That's as far as we can go with facts. How it got there is interesting to consider, but involves pure
speculation.
Okay, I'll speculate. Of the first ring countries around Afghanistan, three are former USSR republics and it seems unlikely that they would have had any North Korean weapons, since the flow would have gone in the other direction, USSR to DPRK. Both Pakistan and Iran established relations with DPRK in 1972 and Afghanistan in 1973, after Khan seized control of the country. Pakistan and Iran are two of just 24 countries with an embassy in Pyongyang and two of 46 countries hosting a DPRK embassy in their country. Afghanistan has neither of these formal diplomatic establishments. If a shipment of arms was sent to one of these countries from NK I would guess it would more likely be to Pakistan than Afghanistan or Iran, since Pakistan was perhaps more desperate for arms in the 60's and 70's with respect to its ongoing wars/skirmishes with India, and recent separation (1973) from Bangladesh (formerly East Pakistan). Iran was a US ally during this Cold War period, so I doubt that they would have received arms from NK. The arms could have gone directly to Afghanistan. President Mohammed Daoud Khan did tilt toward the Soviet/communist sphere from 1973 to about 1977 when he asserted greater independence from the USSR (probably his death sentence) and they did receive aid from the USSR and perhaps other communist countries.
Of course, if the North Korean SKS(s) came in on the black market arms trade to the Taliban or one of the former Mujahadeen groups in the 80's through 10's, which seems to be an even more likely scenario than direct government to government aid/trade, they could have come from anywhere where they were captured, sold, or stolen, perhaps even Southeast Asia.