A friend just gave me a stock and wants to know what it's worth. It supposed to be a orignal XM21 stock used in Vietnam. I know nothing about the stock, I do have it in my possesion. On the butt pad it has a flip up metal plate that rest on the top of you shoulder. It has a number in the barrel channel that is 3793. It has mounts for a leather sling not standard studs. The stock is green base color with camo. I would post pics but don't know how. Any info would be great , and I will try to post pics. What is this stock worth?