You just need to take apart and inspect every single part of the suspension, front and rear, and replace what is worn and adjust what is not worn out.
Spring shackle pins and bushings.
Tierod ends. They need to be thoroughly cleaned and inspected. Make sure balls are round and not egg-shaped. Adjust them according to the Chevrolet Truck Shop Manual.
Draglink ends. Ditto, see tierods above.
Properly adjust the steering box with draglink separated from pitman arm.
New tires would help.
