The ball can be a PITA to adjust. The service manual says it needs to be done with the ball separate from the torque tube and without the cork seal ring, and it's shimmed with multiple gaskets where it bolts to the tranny. You start out with a bunch of gaskets, and if it moves too easily, you remove a gasket and try again. Once it's fairly hard to move by hand, then you take it loose from the tranny and install the cork seal and bolt it to the tranny with the proper number of gaskets. One issue is that if the u-joint has ever let loose, it will tear up the inside of the ball and also create lumps on the outside of the ball. I had two like that and needed to smooth off the ball of the best one of the two so it moved smoothly inside the socket on the tranny.
