The model I chose for this conversion was SIKU no. 3258, a 1:32 scale diecast model of a Fendt 936. The model has quite good detail however the main reason I chose this was because SIKU models are generally made from various diecast parts screwed together which suits modification to radio control perfectly.
I learned from the Massey and decided to use lower voltage battery which removed the need a voltage regulator and all the problems associated with that. That meant I had to squeeze less components into the small tractor and could power the tractor with a battery from 3.3 to 5 volts. This worked well with my original design but I have since moved away from the XBee radio modules and now need to upgrade the model to use the NRF24L01 radios.