no its the cups from the tranny to diffs front and rear. they get worn by getting notched out from the dog bone. yeah i got a bb. when the drive cups get worn to bad they snap the head of the done bone off cause they get caught in the worn spot and cant move around.to get the most out of them ive been putting little bit of gas line in the cup so the dogbone doest get caught in the notched out spots. good temp. fix anyways. the last set ive probably got 10-12 runs on em. so ill need to be replacing them pretty soon. i dont know maybe i just need to take it a little easier on it. i recently had the owb in the tranny crap out on me witch was a little odd. the tranny wasnt that old. i was gonna try some hpi drive cups to see if that helped. we'll see.