Nevermind sorry I confused myself. X-Factory made a 4WD conversion for the Associated RC10B4 and they also made a Belt Drive Conversion for the XXX-4. Sorry for the mistake. I didn't mean to get your hopes up.
Heres the Feigao brushless motor you could go with for a cheap BL setup in your truck:
http://www.hobbycity.com/hobbycity/s...idProduct=5345
Sorry About That,
Spartan