94 k1500 suspension knock

Have what sounds like shock knock coming from the front right when traveling very slow on a bumpy road. Just prior to noise starting, I hauled a very heavy load and front end did float somewhat. Front right side also is sitting 1/2 inch higher than left side now. Replaced a shock -noise went away for awhile - I think. Noise back, new shock appears OK but haven't pulled off to check, have checked upper and lower balljoints and control arms, have greased everything, torsion bar looks sound. If replacement shock is bad, what has made two of them go bad?
Need help. Any ideas?