The torsion bars can have an effect on each side on the rear.
My friends and see if your driver side front was lower or that torsion bar had less tension on it the rear passenger side would lift up a little bit.
Same for the other side so what this means is you might have to fiddle with it and play with your front torsion bars to get it like you want it.
Just remember that when you're loosening or tightening the torsion bars Jack the truck up first to relieve the tension on them.
Too many people don't know this and they strip the anchor out.