Eaton Fuller 12 Speed Auto

I have a 2020 KWT680 w/ a Eaton Fuller 12 Speed Ultrashift. My last trip north, around 50-55mph and 11th gear started growling but would clear up as I went onto 12th.

I delivered and took the truck to the Kenworth dealer in Mokena, IL. They diagnosed it as needing an alignment (it does, I knew that) and the motor mounts “coming out.”

I flew home and then back after a few days and picked the truck up. I took it out for a test run on I80, variable speeds, felt the transmission cycling smoothly, etc.

So I reloaded at my broker and left. Literally 1/2 mile, the rumbling/growling at that same gear and speed occurs.

Opinions? I don’t have a river of cash to throw at this thing as the dealer already charged $3900.

I have been told it can be an output shaft bearing. Anyone know how big of a job that is and what it will run a fella these days?

Thanks in advance for the input.