Tim,
I just sold a set of 4 of these for cheap from a tractor that I am parting out.
To be honest, I have never seen these things wear out past the point of using them. Take them off and clean them up. I bet you find there is very little actual wear in the spherical joint. Get new rubber, tighten down the castle nut good and pump them full of grease.
You won't have near as much play as you think you have. The boots are about 8 bucks each from the dealer. You should be able to salvage the round metal ring that holds the top of the rubber in place.