I am going to be upgrading the rear end in my car since the seal is leaking and cant afford a 12 bolt at the time nor do I really need one. Which posi unit works the best? Eaton, Auburn or Torsen? What comes stock in a 96 Z28?

 

I am assuming you are referring to your pinion seal leaking. Is your stock posi bad? If not there is no reason to change out to another one. If you have your heart set on another posi than I would recommend going with an Aurburn (I think they are rebuildable).