As far as the lift arms, I have seen the weld on ball/socket ends at different tractor supply houses (Agri-Supply, Attwoods, TSC)that you could cut off your Cat 1 and weld on Cat 2. As for the 3rd arm, just buy Cat 2 and swap them. Should be just a swap assuming you have clearance at the tractor for the larger ball end. Might have to grind it down a bit for clearance. Sounds like maybe a two hour welding job at most. By having the Cat 2 balls on the arm, just buy some sleeves and you can still hook it up to the cat 1 pin. Just grease the sleeves good before putting them in otherwise you may have to cut them out with a torch after they corrode up (dont ask me how I know this)