You're on the right track. Caster adjustment is important, and also toe-in (the only 2 adjustments you have, practically speaking). Also check your tires. Not one thing about the AD truck front end was designed for short wide tires and that can and will cause varying degrees of problems. Taller and thinner is better. One other thing to keep in mind...if you have taller tires on the rear and shorter ones on the front, your caster is instantly off. Manuals will tell you your caster ought to be around 2 degrees (1 3/4 plus or minus 1/2 degree), but I've learned over the years that a simple 3 degrees will keep your front wheels in a straight line better. If you get to 4, you're going to need strength or power steering. BIG HAIRY IMPORTANT NOTE: There are locating pins on the bottom of your leaf springs. These make certain the front axle remains locked in place. It is imperative that the locking pins do not get shrouded nor hidden by the caster shims. You want shims that have smaller holes and which are designed so that the pins (you will replace them when you change the angled shims) sit on the bottom of the shims and connect completely with those pins. In other words, your new shims become part of the spring leaf assembly. I've seen a couple of situations over the last 50+ years where people ignored this, and if bumps are hit, if brakes are put on harshly, if the U bolts work loose or weren't tightened properly...that front axle can become what causes a terrible wreck. Good luck.
