P33, does your truck have the driver's side spare tire mount and is it a 1/2 ton model? If memory serves me right, there was a spacer on the right side only between the leaf spring pack and the axle tube mount. This lowered the right side to match the weight of the spare tire and bracket assembly on the left side. If your side spare is gone and/or mount removed and the spacer is still there, it could be the reason.

As others have said, worn springs and/or shackle pins, shackle bolts can tweak the rear look too.

Steve

Last edited by sstock; 01/26/2019 3:26 PM.
1953 Chevrolet 3100
261 cu inch, sm420, 3.55 rear, torque tube still,omaha orange, still 6 volt, RPO green glass, side carrier spare, all done
In the DITY Gallery
Video of the 261 running

1964 GMC 1000
305 Big Block V6, sm420, the next cab off restoration