i purchased my 85 iroc H.O. a few months back. i checked all the numbers and it says it supposed to have posi. i dont think its posi. i only get 1 wheel spinning sometimes. i jacked it up and spun the wheel and the other wheel was spinning the opisite way. a few months later, i jack up it and spin the tire and the other tire doesnt even move.

what wrong with my rear end?

 

Pull the cover and take a look. Probably needs the lube changed anyway.