Have a leak in 727 trans since rebuild. Have browsed many threads, looked at what others have posted, and checked to see if mine is leaking from same places mentioned too. I “think” I have determined it is leaking from gasket cover for output shaft bearing on rear tail shaft housing. How much fluid should I expect to get out of here if I replace? Car is jacked up, rear end higher than front. Thanks for the help.

Very little if any with the rear raised up.

That gasket will almost never leak. Look real close where the rear band pivot shaft goes into the case. Reason I say this is taking the tail shaft housing off is required to remove the bands pivot shaft.Look closely you most likely will need a mirror and clean it well and watch.

Asking for a friend... If a leak is at the rear band pivot shaft, what is the repair process?

the dirty, cheap repair is to super clean that area, then fill that area with a quality RTV or silicon adhesive.
the proper repair is to remove the pivot shaft and replace the shaft o-ring, which requires some disassembly of components, such as the tail housing and valvebody among others.

I did the quick and dirty method and it was leak free for years, still holding up when I changed out to a 518

Thanks for the replies. Ended up finding it was speedo internal o ring.