Based on the responses...
...not many know where the TCM is which is a good thing. IF you need to track yours down, it's above the driver's side rear air bag tucked inside a protective steel shell. The shell is attached with 4 self-tapping screws and I assume the TCM as well. This is for my Tour Master and I'd assume other similar diesel pushers as well.
If you need to locate yours and it's not where mine is, find the output speed sensor, and walk the wire harness all the way to the TCM. The harness is usually only 4' in length max. Good luck.