Hi, I'm building a Polish AKMS and I'm hoping to build a semi accurate rifle from 1988.

My question is that on the Barrel Trunnion and on a 1988 production rifle, where the serial number is engraved, I know it starts off with "1988" and I'm wondering what would the TWO following letters be?

Would it be something like...  "1988 CS12345" ??  

Is "CS" the correct letter codes for a 1988 rifle or is it something different?

On a 1985 production rifle, the SN would be "1985 SP12345"   and for a 1983 rifle, the serial number is "1983 SL 12345"  this is the only date codes I can find on a Polish AKMS rifle.

Thanks for any input in finding out the right letter code for a 1988 rifle!!