You might ask the dealer what cross-caster setting is in the truck. Cross-caster (the difference in caster between the left and right wheel) is normally dialed into the truck to make it pull slightly to the left if you run it on an absolutely flat surface - this compensates for road crown. The truck will pull toward the side with the least (most negative) caster. If it's pulling right, it may not have enough cross-caster. This is, of course, assuming that the other alignment settings are right and that there's nothing wrong in the rear (tire pressures, etc. ) that could be causing the pull to the right.
Also, check to see if you have a thin spacer between the right front wheel and hub. If so, you can remove it or even shift it to the left side. This is a band-aid used by Dodge for "pulling" complaints - the truck will pull toward the side with the spacer.
Rusty