One thing to consider also thirtysixhundred, are the rivets on the spring hangers (believe me, I found that out quick ). My 49 1/2 ton did the same and after trying and adjusting everything I could it was not traveling straight, till one day I tore the entire front end apart and realized that sring hanger was crooked (no tension from the springs ). I could rock the hanger with my hand with the rivits in place!...I grinded the rivets off and installed grade 8 bolts and now she travels straight as an arrow. Now I need to rebuild my steering box but that's another story......hope it works out and good luck...keep us posted
