I had problems with my 58 even after installing new king pins. Tied rods were adjustable, but tight. Steering box didn't have play, yet it was a wild ride to go down the road.
One day I had the front end in the air with the axle swinging and realize the spring shackle bushings were worn out letting the front axle move back and forth.
Replaced those spring shackle bushings and it's been good ever since.
