a 727 or 904 transmission is pretty easy to rebuild. just pick up a copy of the Monroe book, plus a manual from the ATSG for your transmission. then get the upgrade parts you need or want, and have at. if i can do one, anyone can.
i should have posted a link for that. sorry......... the other thing to keep in mind, is "cleanliness is next to God....." in other words, keep everything CLEAN, CLEAN, CLEAN !