The rear clutch bearing is 5x13. The front clutch bearing is the smaller 5x10 which is a standard size for most buggies. www.carolinasrc.com sells 10-packs of both. For the front bearing, I run ones with a rubber shield facing out with a metal shield on the other side. This helps keep dirt out and helps dissipate heat. I run full metal shielded bearings for the bigger one for better heat dissipation since it's not as exposed as the front bearing.

Alloy shock caps are a good idea since those are a common weak point on the RTR.