What are the u-bolts that you refer to? It sounds like you have two and one is giving you problems. It is not clear what you are referring to.
There are four bolts that hold a collar/cover to the rear of the transmission. Have you loosened those and slid the cover/collar and ball/"bell" backwards over the tube?
If yes, the u-joint's two, front, trunnion bearings are each held on with 2 cap screws per trunnion bearing (four cap screws/bolts).
Here is a photo the collar/cover and ball/bell that cover the u-joint. The u-joint looks like
the u-joint at the lower right of this illustration. The transmission would be to left of the u-joint.
