Don't forget to check the drag link and steering box. Weak springs could be a issue. Are the front shackles nearly vertical, or splayed toward the front? I had the similar issue until I had the springs re-arced. If this is a working truck I'd go with new springs. My 41 sometimes sits for 2-3 weeks and it takes 10 miles or so for the flat spots in the tires to work out.
