Your sling may be post war Austrian (there were no differences but a stamp) but for 35 bucks you did fine!
It does not appear to be a cut down 98K sling. The milled steel button looks post war. Early steel German buttons were milled and had two flat inner surfaces, with generally one flat outer surface with the other convex, or two convex. They were well made. This one has two convex surfaces against the leather.
You find the stamped end pieces on the friction bar after about 1942. Before that, the bar was a single milled piece.
Not all MP-40 slings were marked or cross-hatched. Here are pics of one of mine. You can see the makers mark and dimly see the MP 38 u. 40 stamp, which doesn't survive on well used examples. The sling is original to my all matching bnz 41 MP-40. The sling was made in Austria to German specs. It has no cross hatching.
Edited by TSMGguy, 20 July 2019 - 07:52 PM.