Pulling Fuzion toy hauler my transmission started shifting erratic. It shifted up and down when pulling any kind of grade, would hang in 3rd gear, then upshift hard into next gear. Even downshifted to 1st gear and pinned engine on rev limiter. Was really dangerous. Huge wrench appeared on dash display, trans temp went over 250 and it was only 60 degrees outside.

Dealer tried valve body, but didn't help. Pulled trans, all forward clutches gone, did complete overhaul. Felt trans should have been replaced completely as truck only had 15k miles. I've had several F350 trucks with same running gear and never had issue, and didn't find any history of common similar issues online for such low mileage truck.

I have 10k miles on rebuild now, trans seems to hang in 3rd gear on downhill descents, when you get back on throttle it stays in 3rd, to extremely high rpm before finally shifting, unfortunately I believe this is how it started when trans failed,