I've got a 9" rear with a posi unit. at least that's what it was when I took the diff. case out of the housing...Now, after I put it back in, both axles seem to bolted in place, but when I spin the yoke, only the driver side tire spins. When I hold the yoke still, and spin either tire, the other does nothing. It acts like the passenger side axle just isn't inside the diff. case. While it was out, I put both axles in, and it worked great outside the housing. Also, the splines on both are fine, and the diff. gears are all fine too. Anyone had any experiences like this? Or have any ideas what's wrong with it? The car drove fine before I took the diff out, but the posi never did work before...help..?