You NEED a press, bearing splitter, various pullers and snap ring pliers and a FSM. You can make some of the special tools.
Google "rebuilding r151f" I don't have the link anymore but there is a good write up with pics I "think" on Pirate.
I rebuilt my R151F and fabbed a bracket to hold the trans properly on the press and IIRC three different diameter pieces of pipe were used to press various sections apart or together. I have large 3/4" drive sockets that also come in handy to press various parts and seals on or off. All the info was in that thread.
Download the FSM as a guide and take pics. Pay close attention to the detent balls and pins in the linkage.