Looks like a 3/4 ton is 1/2' and the larger ones 5/8" bolt and the ball is 1 1/16 larger also. I doubt if anyone has reproductions I have seen them on eBay and there is very little interest, but that is like searching for a needle in a haystack. There are probably some around, but people don't know what they have. Since you have the dimensions, a machinist could turn one. There are a few small town machine shops left that will still do something like that reasonably.