I rebuilt the A-413 torqueflite in my minivan. I understand it is almost identical to a 904/727 other than the 180 deg output turn and differential. It was my first tranny and easier than I expected. I have re-ringed engines before. I bought the Mopar "Diagnostics and Service ..." book off ebay for ~$15. The other book from a company (forgot name, TSI or such) is just a lesser copy (~$50). I expect similar for 904/727 (Commando1's post). The book is step by step, with many drawings, so any detailed person should be able to follow it. If you are erratic or a meth addict, take it to a shop. The only special tool I recall is large snap-ring pliers (set from Harbor Freight). I rigged a push lever from stuff lying around (maybe for the A-606 I did later). A shop press helped on one clutch piston, but a weak spring so no need if you have a helper (requires 3 hands).
Make sure you get a kit with clutch plates ("banner kit" ~$80). If you have time, take it apart first and see if you need steel plates ("full kit" ~$120). Usually not. You need a vernier caliper or micrometer to measure (my steels were worn <2 mils, so re-used). Don't get an "overhaul kit", which is just seals. You can order almost any internal part online, often amazingly cheap (clutch plates $2 each). Some get special racing clutch plates (High Energy, Red, Blue Plate, etc), but I don't know if that gives longer life, and costs $$. Seems you almost never need a new rear band (L/R). You may need new tri-metal "bearing washers" that fit between the clutch packs (forgot their name). I suggest an upgraded L/R piston (~$12) to replace the factory one that cocks, and an improved band strut. Search (recall for 727 also).
I think you can stop dis-assembly before removing the over-running clutch (rear of case). If you do, the rollers and leaf springs fall out. If so, insure you face the leaf springs the correct way. It is tricky getting that back together without the factory "installation ring" to hold the rollers in. I used a sheet-metal wrap, grease, and gravity (rear of case up) to get mine back together. I didn't have tranny grease, so used Vasoline. In my A-413, I had to replace the output bearings, but that was because a prior rebuild shop did crap work (left off nut retainers). They also re-used worn clutch plates and doubled up steel plates to make that fit (last thru the warranty). I bought that tranny from a junkyard. It had a "Certified Transmissions" rebuild label.
If still scared, you can find several videos on YouTube. You can also buy clutch packs pre-assembled, if that part scares you, but they are real simple to take apart with just a flat screwdriver. Still, I have seen great deals on new ones on ebay (~$25). I once took a 904 out by hand, but now have a Harbor Freight tranny jack, which makes it easy and is useful for other things.
