After looking around I may need to seek a different supplier as just the Tamiya gear (which is most likely too wide) on eBay is not really cost effective and I think looking at a toy RTR might be my best avenue. They do make 4X4 toy trucks!!
AND... while in the neighborhood I want to also look into powering the front axle making it a 4X4 or a 6X6 and this could get a bit salty in a hurry. 3 axles/rearends, driveshafts and a transfer-case... plus most likely a different motor and ECU is pretty obvious.
Either that or just buy a Tamiya tractor as a donor and get that Dragon Wagon resin cab kit?
Jeff