If you have a pro shop rebuild that 400, they will disassemble it and carefully inspect every part in it for proper fit. If there is any doubt about any of the hard parts or bushings they should be replaced. Usually a bushing kit is a very good investment in any transmission job, and if there are chunks breaking off of something it should be replaced. Ask around about shops in your area and ask them how much to disassemble it and to give you an idea what it will take to rebuild it. Like an engine, you really won't know how much until everything is cleaned and checked. Most anyone can throw the frictions and steels in one, but that won't last long if there is anything else that is bad. Get ready, it probably won't be cheap, but a 400 is nearly bullet proff if done right. Good luck
