[special-K]

The camber is not supposed to be out from factory. That old timer is wrong. I have never had to do it on any of my trucks,but as mentioned there are shims for between the spindle and knuckle to correct camber. Naturally,the first thing to do is be sure you have healthy bearings and ball joints. I have only ever heard of camber being off with the top tilted in and wearing the inside of the tire. I always figured those trucks had a tweaked axle from coming down hard on it. I can't imagine anything that would tweak an axle in the opposite way.
Is you truck lifted? Maybe the axle is rolled forward to compensate for drive shaft angle. When that is done it's also necessary to clock the "C"s (axle ends where ball joints are) back to vertical for proper steering geometry. This will cause too much toe-in and wear the outer tread.