Im sure within that cabus thread someone has contacted to a challenger via the canbus socket.
If it is steer ready over canbus the canbus pcb would probably be the best to go for.
If its not on canbus then you could still use the tractors steer ready hardware but the aio pcb would probably be best as you can wire up the steering valves directly to the ampseal connector and all the existing hardware.
Might be best to put up some more information on your tractor, the age of it. Some pictures of the steer valve and the diagnostic plugs in the cab and im sure someone will be able to advise
Theres a few posts regarding the challenger if you look towards the endish of the thread scrolling through slowly