Nice ride. There are a lot of x1 crts out there.
Mine came with a six gear spider diff with a 52t spur. Not sure if I can change it so I am running it. Good luck with your build. Also I fit a traxxas water proof reciever box where your reciever is.I used a e maxx one but think the slash one is a little smaller. Drilled and tapped the servo plate.