vented slipper:
http://www.amainhobbies.com/product_...lipper-Hub-Set

High torque slipper pad:
http://www.amainhobbies.com/product_...pper-Pad-Set-2

go halfs with a buddy as you get two of each item and only need one each

the vented slipper replaces the outside/rear one as does the high torque slipper pad, outside/rear one.