To my knowledge (this is my opinion) that the letter "K" was the last year of Russian SKS's produced by Tula. I have this rifle in my collection that was manufactured with a original laminated stock with recoil lug in the wrist of the stock. These stocks are quite different from the replacement stocks that were put on during the rebuilds. The original should have the dark orange-red finish with serial number and proof marks on the left side of the stockand the wrist of the stock is much thinner in this area. I will have to check as I think I have two of these in my collection. I also have another original laminated stock letter date Russian "D" that looks like a "A" with a flat top and I have one with original hardwood stock in the same letter date.