Well, a chassis manual is always a good reference and will take you through disassembly and reassembly. There is also a thread that a number of us had input on that can give you some suggestions. It should be in the link below. ST400 It is for the Switch Pitch trans, but should cover most items for a standard TH400 as well. Mark
I hope that thread can help you.......it was more work posting and editing those pictures than the tranny rebuild was! :laugh: Trust me on this one, if you can pay close attention to how things come apart and go together you'll be fine. It also doesn't hurt to have a factory service manual handy. The most important and confusing thing is the placement of all those needle bearings and thrust washers.......and aside from getting the clutch pistons in without cutting the seals, the rest is easy.....really. Just take your time and don't try to rush the job.
Many speed shops, parts stores and regular book stores can get trnas rebuild books for you. I bought my th400 rebuild book from Jegs in Ohio while visiting friends. It was cheap $15.00(?). I could have gotten it locally but I happened to see it on the shelf while we were there. Try online, or ebay. Having a book in front of you when doing this is easier than brining you tranny into your computer room.
I can also recommend "How to Work With and Modify the Turbo Hydra-Matic 400 Transmission" by Ron Sessions, ISBN: 0879382678 Devon