Actually each of the parts I've ordered have come with an Allen wrench, but I also ordered a 0.050" driver. Everything seems to be the same size, and everything I've messed with is threaded (no nuts except for the wheels).
Bennett's first motor swap. Camping in Clemson the kids ran them both hard. He brought them both to me and said they quit. I assumed they killed batteries in both so put them away. The next day put in fresh batteries and the white one ran but the yellow one did not. After messing with it for a little bit it started running but was slow, then it cleaned up and was fine.
For a couple more days it would run fine then quit randomly. You could spin a driveshaft and it would go again for a while. Then it quit all together. I emailed Axial but went ahead and ordered another motor from amazon for $9... Figure if Axial sends me one I'll have a spare.
While it was apart, I went ahead and put the aluminum rear housing and shocks in. Gotta get that backlash just right...
I was hesitant to do the same upgrades to the white one because of weight. With just the aluminum parts on the front of the yellow one it felt significantly heavier, but after putting the rear in it felt pretty balanced. I weighed them both last night. White one is 8 oz, yellow is 8.6 oz. Really small increase for aluminum axles and shocks.
Found a pair of overdrive gears for $16 last night so went ahead and ordered them to put a set in the front of both trucks.