Sam I take it this isn't the one for a 3/4-ton we saw on eBay. On a 1/2-ton there is only the one side brace at the front of the bed unlike a 3/4-ton which has another just in front of the fender.
I was concerned that a mount made for a 1/2-ton might now work well on a 3/4.
As for the studs for the wheel, you might mark a third location using the wheel, drill a hole, and put a bolt through from the rear and then bolt or weld it in place.
