on my 51 3100 by using a floor jack i was able to raise the torqtube up aganst the floor board slide the ball or bell back and then lower the torqtube down to line up the u bolt and bolt it togrther slide the ball and bolt the retanier and button everthing up
This is what I do when I am removing or installing the gear box, with jack stands under the rear frame members which allows the TT to pivot freely.