Just purchased set #2 for the 5500. IMHO the best addition to my tractors. If a MFG wanted to blow out the competition - they would offer a PATS style end instead of the ball as a option. Most category 3 is a quick hitch type coupler.
I have thought about cutting the balls off my lift arms and welding the PATS on (availablr thru Greenwell Mfg).
My brother has a QH and had to modify some of his equipment and all of the toplink to work. With PATS, any 3PT attachment will work w/o major modification.
I did add a bent washer to the bottom of the supplied washers to keep them straight on the pin. Also made extras using 2 bent washers welded to a 1" flat washer for the hitchpin.
Also, the pins on my boxblade were sloppy and I replaced with a longer pin and welded a flat bar back to the frame to create a clevis hookup. Back blading will wear out the pins on BB quick and a clevis hookup works!