Has anyone ever used them? any problems with them? My brother has one on his 02 chevy 1500 z71. lately he has been hearing a grinding noise, he pulled out the magnet on the dip stick to his rear diff cover and it is full of medal. he is going to pull it off to look an see whats wrong with it. i was wondering if the cover could be the problem? i dont think anything is rubbing on the cover because it is a lot bigger then the stock so there is no rubbing on it.