Judging by these paragraphs in the service document that was posted:
"On 2500/3500 pickup trucks, (DJ and D2) the in-cab controls, chassis wiring and TPM receiver module have been factory installed. The module is located behind the rear license plate. A kit containing all required hardware for the sensor installation is provided and can be found in the cab of the vehicle.
On 3500/4500/5500 chassis cabs, (DF, DD and DP) the in-cab controls and chassis wiring have been factory installed. The customer is responsible for installing the TPM Receiver Module. Kits containing all required hardware for the sensor and module installation is provided and can be found in the cab of the vehicle."
I'm optimistic the module inside the cab is already there since the wiring is at the bumper already, maybe the module in the cab controls the truck TPMS as well, and all that's needed is to add the trailer sensor to it and enable it. But i guess we'll find out when
@brutal or I get the module and plug it in.