Originally Posted by
TwoTone
I'm not sure if people still do this, but while I'm building them, I stick an allen in each diff half and hold those while trying to rotate the pully, if it moves it's slipping.
i do it the same way Two Tone does it but i recheck after i put it on the track and hit the throttle a cuople of times to make sure no slippage and make sure you break the diff in also