Wll today i finally broke a center drive shaft. It took alot of bashing, I was expecting to change to CVD's long ago. Anyway when I had the cover off exposing the rear diff I noticed a small allen screw on the gear hub. I attempted to tighten it , but it seemed to be like the one on the transmission where it is an ajustment screw. Am I right? Also what kind of greese should I put on the Diff. and how much?