Nice CHICOM !! One of the Top 3 if not not Top 2 SKS rifles on the planet! Good deal you got there for a machined-recvr combat-proven battle rifle.
Go here and start reading, tons of good info;
You'll learn that of the dozens of Chinese arsenals producing the SKS for the PLA, only Arsenal/Factory 26 has information that folks have used to deduce the mfg dates of Arsenal 26 guns.
This is based on the supposition that since this arsenal was established by the Soviets for the Red Chinese, the arsenal 26 guns have codes that are likely in the same formats as the Soviets used on their own guns.
So, only these "Sino Soviet" SKS can be maybe/probably/possibly be accurately "dated".
The long and short of it is that CHICOM SKS rifles flooded the USA market in the 80's by the bajillions - some with U/F spikers, a few with U/F blades, some in a mix of wood and bakelite. China's declaration of obsolescence was our gain as they are built to Soviet specs and meant for combat; you will enjoy yours.
Be sure to clean it - maybe at least check it 3 times. Cosmo is everywhere on these guns, especially inside the bolt. They have been known to slam-fire due to coagulated CHICOM-chapstick.
I bought a used one once and was told it had been fired. I took a nightcrawler-looking blob of cosmo out of the gas tube.
No way it could have functioned - maybe that is why it was in a pawn shop; "it didn't work"... Now its mint/perfect.