well, i did it. i rebuilt the c6 in my 77 f100. it was a lot harder than i expected. my inexperience and screw ups are what made it hard. i found that a c6 isn't so complicated. i didn't find anything broken or very worn. i did find some very thick slouge in the valve body and servo. now it goes into reverse quickly and down shifts as one would expect. while i was at it, i installed a shift kit. i selected the rv type shifting. i think it shifts more crisply now.
anyway, and once again, i realize we don't pay our mechanics enough.
btw, i have the video guide to rebuilding the c6 if any of you are interested. i want $15.00 for it. it was very helpful!