So, as it seems to be a trend around here, I am rebuilding my RC10t that I built when I was like 12. I really enjoyed building it back then and about 10-12 years ago my brother got a couple new batteries and electronics and ran it a bit. Then it went in a box in the attic and has sat until my son turned 4 a few days ago and he received a bunch of the cheapo walmart rc cars. I decided to pull it out and see if it ran. Batts were dead and it would only run for like 3-5 minutes, but everything else seemed to work. The plan was to get a couple new batteries and a charger that I dont have to turn the dial every 15 minutes....~$350 later I am building a 9.5t brushless with 3s lipos..

Will any 48P pinion gears work with the stock spur?
Am I doing to demolish the stock diff and/or trans with this setup?
Now some pics from before the teardown: