It's been a long time since I worked in a big truck shop but we did a lot of axle bending for alignment purposes. Some trucks had been wrecked and some were misaligned from the factory.
Find a big truck shop willing to work on your little truck axle. Modern trucks still have straight axles so I'm betting they are still aligned with shims and Port-a-powers and chains. Oh yes, and heat. Also remember that the arch of your front springs and the load on them will affect caster.
