I just got through installing a steeringclutch.com disc in place of a chewed up Cat version. Quality appeared excellent and so far so good but I have only used it a couple of times ( D4 dozer/winch tractor). The earlier discs (before 7U 21xx) were a disc assembly with friction faces attached to a steel plate. I think I would consider the earlier versions to be a better unit if you can get them refaced or find one in good condition.
From what I hear the Cat unit is now closer to $500 and our local dealer was almost embarrassed to quote and tipped the buyer off to a $100+ source.