[dsraven]

here is something to try by yourself that will take only a couple of seconds. if you don'y wanna do a dry turn, like turning the steering without the truck moving, then simply jack the front wheels off the ground. use wheel blocks so it can't roll away off the jack or, more safely, use jack stands to settle the truck down on so the wheels are off the ground out front.
now, simply start it up and turn the wheel from all the way right over to all the left which is what is called lock to lock. counting the number of turns this takes simply turn it all the way to the lock in one direction and then turn it back the other way half the number of turns it took to go lock to lock. while holding the steering wheel in this position turn the key off. ensure the steering wheel stays in that position while you get out and look at where the front wheels are pointing. they should be straight ahead. if not return to your wheel alignment shop and ask them to do the same thing. also ask why the steering is not centered, maybe they have an answer,maybe they simply opt to redo the alignment citing some reason or another. also, just a heads up, with the steering centered your steering wheel should also be centered. if it is not correct I would be looking for a better quality alignment shop for athe next time you need one. a lot of shops, like parts places, need to have a vehicle make model and submodel in order to dfo an alignment. without this they are lost. it is harder to find a shop that can fly by the seat of their pants these days. if you have the specs handy they may find it easier to set it up.