I would have the alignment checked by a shop that has the equipment to do a FOUR wheel alignment.
Do not fall for the story that your rear axle is not adjustable. That is mechanic BS meaning that the shop does not have the equipment to do a proper four wheel alignment. It is adjustable and if the trust angle is out of adjustment on the rear axle it does not matter if the front axle is perfectly aligned. The rear axle will still tend to push the front sideways, causing outside wear on your tires.
You may have to take it to a truck service center to get the alignment done but it will be worth it to do it right. Here is one link that explains thrust angle alignment.
Thrust angle alignment
