Hi, My 49 1/2ton had the same problem . When my dad had the truck he took it to a few shops to have it checked out ,nothing was found, then last year I was under the truck on jack stands doing a oil change( no creeper) I went to pull my self into another position I grabbed the tie rod and herd and felt a clunk. I found one tie rod end had play in one position, it would let the tire change toe about 1/4 inch.
