90 b2200 alignment questions

I was told by a shop when i was getting my truck aligned that my camber cant be adjusted because it's too rusted. They said they put my caster and toe back to spec. They also said that I would need a front alignment shim kit. The truck pulls to the right pretty good and the outer edge on both front tires is damn near bald. The pass side tire is a little worse. It feels a little better now but still pulls to the right. So to me it sounds like it has too much positive camber. But they said that it needs a shim kit. Does this all sound right or are they yanking my chain? And how do you replace or add a shim kit?

The camber adjustment is done where the a-arm bolts to the frame. To adjust out some off your positive camber, shims are installed to move the a-arm toward the center of the truck. If everything is too rusty, spray it down with PB Blaster the day before you go for an alignment.

^x2