So I'm replacing my father's 1981 300SD's alternator, getting towards finishing, when he comes over and says, "Hope that tensioner bolt don't break..." Well, you know what then happens, right. The bolt was originally slightly twisted (guess the PO didn't know to loosen the mounting bolts first) and I can't get that special nut off the broken end of the threaded rod/bolt. I tried figuring out what the threaded rod/bolt was but I can't get any nuts of any size or pitch onto it. So, anyone know what the size(and pitch) of that threaded rod is... the one that has that special nut on it that you use to loosen/tighten the alternator belt.... you know, the one that's welded onto the side of the head of the mounting bolt? Thanks.