To dismantle this transaxle, a special wrench is needed to remove the finned differential retaining nut and not damage the aluminum fins. The dimensions were found and a drawing created. The parts were cut on the ProtoMax, except for the steel tubing, and consist of the starred wheel and the insert for a 3/8" ratchet.
A few welds to hold it together and a quick coat of paint finish it off.
This nut is not under a lot of compression, so the wrench doesn't have to be heavy duty. The starred part was cut from 1/8" steel plate and the insert for the ratchet cut from 1/4" steel plate. The tubing is 1.5" x 0.120 wall steel. It could have made it out of aluminum, but my welding skills are not that good yet!