1973 Opel GT
Looking through the FSM, there was a specific tool to help with removing the universal joint's pinion flange from the propeller shaft inside the torque tube. Two bolts (J-8614-10 or J-44873-2) would secure the flange holder (J--8614-11, the large wrench-like tool) while the flange remover (J-8614-2, positioned between the flange holder and the pinion flange) used a screw (J-8614-3, called a forcing screw) to push against the propeller shaft. This tool works similarly to a pulley remover. Chances are, this wouldn't be a tool used regularly in a home garage but could be a useful community tool. It still can be sourced today, at least if you're patient in finding the parts. A similar tool wouldn't be hard to create either, but this is a curious tool. It seems that the flange holder is the expensive part of this kit.