I found a way to mount the 36v pack in the truck. I also took out the 22 teeth pinion and went with a 14 teeth one. If everything goes well with the 14, I'll switch back to the 22 for some speed runs.
I just came back from doing a quick test run. The spur, pinion gears are fine. The front diff is fine, but the rear locked on me. The ESC and motor only got warm after a little over 5mins. of running. I'm thinking of installing a 16 teeth pinion, but I'll probably go with the 22.