That looks like a quick hitch,
a local guy makes them in a small shop, and he only sells to dealers. PM me and I will give you the number of a local dealer.
buy the way, the ball has a t-shaped shaft (that fits in the slot) and the upper part of the shaft has a giant threaded nut with flanges you hit with a shop hammer to tighten or loosen. Its a dang good hitch, rated at 30k, I have had them in a couple different trucks the only reason I dont still use them is the B&W is easer to remove.