I jacked up the rear end of my car today to check a brake I had dragging. Turned out to be a broken bolt on the e-brake cable guide (easy enough to fix) but found another potential problem- I spun the passenger tire forward several revolutions, and the other tire never moved. I watched my driveshaft to make sure it was turning, then repeated the process on the driver's side wheel. The other wheel never budged. What do you guys think? Shelled differential? Its an 86' n/a, so has an open diff (or should- questionable history on the car). The rear pulls to the right when I hit bumps, so I'm thinking of replacing the half shafts and putting in solid bushings for the cross member and diff. Help appreciated.