Purchased truck and I never paided attention to it very much. I thought it was because it was sitting on a not level surface at the time. However, if you looked at it straight from the back end, it was obviously noticeable. Very!

I tried putting lowering blocks to even it out, buy lowered springs but it still did not fix the problem. And it became annoying and getting expensive. I asked other GMC similar truck owners but they didn't have my obvious problem.