For what it is worth, your shop manual tells you the caster ought to be a max of around 2.25 degrees. Over the past 55 years of messing with these, I've learned they actually handle best if the caster is between 2.5 and 3 degrees. And one half of a degree does make a notable difference. However...please keep in mind there is a trade-off. The greater your caster angle is, the straighter your truck will run down the road. Also, please keep in mind the greater your caster angle is, the harder your truck will be to steer (in town, especially). The reason is because the caster angle means all the weight of your front end sits on top of an angle and when you turn your wheels, you're actually lifting the truck up. So there is a trade-off...2 or 2.25 degrees is okay. It means your truck will steer easily and will be reasonably straight while driving down the road. And remember...these trucks were designed to be driven between 50 and 60 mph. Little or no caster angle means your truck will steer easier and also will wander around like a drunk billy goat.
