These tech guides contain the "theory of operation" specifically for the 6L80 and 6T75.

They show in very great detail (using very good artwork) how all the internal hard-parts and clutches fit together and interact as the PCM shifts from gear to gear... they show how each component performs it's function, and how each component is electronically/hydraulically applied and released.

They show all the hydraulic passages, all the checkballs, all the solenoids and the valvetrains they control, all the other valves, the pump, the torque converter...

they are not repair manuals, they do not contain any repair information (other than some mild diagnostic information such as "if checkball X is missing then the xyz clutch will not apply")...

if you want to know extensively how these transmissions function, then these are the books
(if only the actual hard parts were painted the same colour... ...)

See the 4 speed RWD section of the forum for some examples from the 4L60E/4L80E tech guides.

Oh, I didn't get promoted... ...I demoted myself from "In Charge of Lost Bolts" (plural) to "Lost Bolt Moderator" (singular)...

Cheers,
Joe