My guess is that you are "passing fluids" from the final drive into the ATF
(a common problem) The heavier gear lube creates havoc within the valve
body/clutches in the transmission.
I don't want to be a doomsayer but you might want to look about and starting
thinking "replacement"
For those that DON'T know, the "rear end" or "final drive" (not something you
take in a hearse) is lubricated by it's own oil suplly that is almost NEVER
checked..
I've also seen the tranny coolers "pin hole" and weep coolant into the
ATF..oh ain't THAT sweet!
One way that the final drive loses it's oil is that the vent on the top of
the case gets buried in dirt and the pressure build up forces out the oil
past the seals etc.
I'm hoping I'm wrong, but it sounds like "dying transmission"

steve...

"Hey! nice Jeep, Mister!"
"Look kid, it's NOTAJEEP"