My 4L85E has never been disassembled.
I value human life over the chunk of aluminum and steel. I had a master cylinder fail in an older vehicle once. It was working well one moment then the pedal was nearly on the floor the next moment. Getting stopped was not fun on rear drums alone, even though I did pull the shifter on the 700r4 into 1st gear at 70 mph. The brake warning light came on after I got stopped and I thought to myself that would have been nice to know earlier, lol.
Steering is also a very important sub system. I had a S10 once that broke a motor mount and jammed the steering shaft coupler against a header primary. That was a very interesting moment. All I could do was jab the brakes as the momentum carried me off the road into the ditch, luckily not hitting anything. I learned from that, if it can possibly move, it needs to stay far away from steering linkages.