Tranny rebuilding isnt brain surgery. The main problem doing it yourself is the clutch pack compressing tools. If you can rebuild an engine, you can do an automatic. Turbo 400's arent so complicated that with a good manual you cant do it yourself. I was always afraid of automatics but I couldnt run on the NHRA record with my stick car so I changed to a glide and ran about 3/10's under.
Built my first trans on the ramp of my race car trailer. When that one worked I wasn't skeered any more.
Give it a try !
