Mines at 119k and the transmission just shuffled off its mortal coil, as well as the TC, it did it the day after I got done with the entire front end, ball joints, bushings, rotors, and the like, its had a water pump at 80k and a new right front wheel hub at 85k.
I spent several hundred miles going through hay fields and off road pulling tractors, and hay trailers so its no wonder my suspension was shot, and it needed new shocks, I abuse my transmission with higher performance tunes and equipment, personally I think its just the attrition of the truck and what we put em through.