Here is will happen to youe sleeve hitch adapter if you don't use a double yoke:
The shiney area was welded to build egg shape hole back up. The holes had that much wear in them from a single yoke system. Aother problem with a single yoke set up is you will have side play in you implement.
I did some research awhile back in the Cub Cadet parts lookup. The IH tiller, box blade and rear blade had support on both sides of the implement's arm. IH engineers saw the problem and had a solution for their products. I'm not a big fan of using a a rod all the way through both sides as Matt suggested. The rod can and will bend.
This is the set up I use:
