Those sling swivels and bases are from a Super Grade or Target Model. The sling has the proper hook for the Eye that would be proper on an early 54 stock as you have pictured. They are a stud with a larger hole than a typical modern detachable sling swivel stud.
You have two sets of swivels on the gun, SG and fishook. Looks like someone took the original swivel studs off your gun and installed SG bases. Just use that sling with the SG swivels.
"When the going gets weird, the weird turn pro." Hunter S. Thompson
here are pics of the rivets and hardware on the sling
The photos confirm all the traits of an original Winchester sling back in the day. Good job on finding that one, since they are somewhat rare and not often seen for sale.
[quote=Demingus]What is it?[/quote It is a "Military style" sling with features that conform to being "Style Correct" for a vendor supplied Winchester #3257 or #3259 sling. Multiple vendors made unmarked slings of similar style for several other rifle makers of the day in addition to Winchester, so there's no way of verifying that this sling was a Winchester supplied sling. I would feel good about your purchase.
