Jeff,
My unprofessional opinion. I do lots of mechanical stuff all day long but the one thing I wouldn't do is rebuild an automatic transmission.
My cousin had a transmission rebuild shop for 35 years. I worked for him when in high school as a flunky, and hung around a lot in my adult years (still a flunky).
There were some special tools, but the real special thing was the experience. The ability to see a thrust washer and know it was worn and wouldn't work, or the proper way to install a quad ring and know you hadn't pinched it.
Maybe I am over 'mystify' this profession as I have always thought this too technical for a shade tree mechanic. I would put my finances and energy into the more mundane aspects of the hobby and leave the automatic tranny to the experienced tranny man.
Maybe I'm too old and not as adventurous as some!
Stuart