Rudy is right. I just spent several weeks chasing a negative camber problem on my 83 SD. I first replaced the subframe mounts and differential mounts with some but limited improvement. I then replaced the trailing arm bushings with no difference. I measured and corrected the ride height using a MR. Gasket #1287 spring rubber as a temporary fix. This made a large improvement. The final solution for me was replacing the passenger side trailing arm as it was much worse and had a deformation that was undectable by looking at it. The Po had hit a curb and put the spare on before selling. I didn't see the dent in the spare until I had completed the repairs.
Hope this helps you.