Jammin Crt .5 conversion??

alright i have a traxxas pede that i recently did a make over on and was stoked to get it out in the dirt. but whati soon realized that two wheel drive in the dirt realy isnt that much fun. so i think i want to get me a 4wd so i wanted to convert me a .5 crt. i was going to get the RTR one and selling off all the stuff that i dont need for the lectric part. what is the diffrence between the artr then the rtr one. also what would you guys reccomend i do while i process? like should i extend it or something? also i want to run 2.2 truck tires maybe some moabs that i have lieing around but thats just for grins and giggles.

well this is what i want to use so far;
.5crt truck
RCM motor mount
fiaego L sized motor
7-8 cell pack
MM
vileneon 3500kv motor
i want to reach speeds around 35mph maybe 40 but not more than that as this is a bashing truck.
so any help on this convfersion would be sweet. also pictures of your converted rides. thanks again