The ways to get things done are a constant source of amazement. I think a bit different from some so take this as an opinion. 3 speed trans mission is light enough to move by hand(that is me under the truck). The 4 speed is too big to move by hand(that is a jack under the truck with me). Undoing the torque tube is messy but not hard(told you this was an opinion right?). Lifting the 4 speed from in the cab(engine hoist) is an option. The rear cross member under the tail of the transmission could use a coat of paint...Pulling the engine is a project. Might as well look at the "U" joint and the trunnion bearing while you are under there. Smile it is only some suggestions. Sulfur in the transmission oil and the third member have been banned from my home and laundry. I use clothes that can be recycled a shop rags for this kind of work. Makes it so much easier to go to sleep at night. That stuff makes the dryer smell bad, so I have been told.

Steve H