What special tools? There's only one I can think of, and that's a jackscrew to release a big accumulator spring. My father fabricated that one from scrap metal around the shop when he started rebuilding Hydramatics in the late 1940's.

The only thing missing about rebuilding a dual range Hydramatic is the skill to do it right.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!