Rear Wheel Wobble

[Ol' Drippy]

I am having a problem with my 94 C1500 2wd truck that I need help with. It has the stock rear end and everything worked fine when it had the original drum brakes and open carrier (3.42). I swapped in a used posi out of a caprice cop car and at the same time welded some brackets on the axle flanges to add disc brakes. Once I put everything back together, I found that both rear wheels wobble back and forth, one worse than the other. I thought my axles might be bent so I replaced them with new axles but the wobble it still there. I also had the rear wheels checked and they aren't bent. The carrier bearings and axle bearings are also new. At this point I am thinking that maybe something is wrong in the posi? It doesn't make any unusual noises. Any ideas?