Truck listing to one side

[Ronw435]

I am wondering if anyone has ever encountered the rear of there trucks listing to one side or the other. My truck with new springs, both springs installed in the same location, has a 3/4" list to the drivers side. Drivers side sitting a little lower than the ps. I have looked the frame over and cannot find any deviation from one side to the other. I had a 2004 GMC Seirra that had a slight list to one side and it was brand new.
Has anyone had anything like this? I was thinking of placing a 3/4' block at the top of the spring to see if that takes it out. I am measuring the height at the bumper which is bolted to the frame.

Thanks for any thoughts on this.

Ron