Sorry to hear you're taking your vehicle to the dealer for repairs.
No, the steering box is not the reason the wheel isn't straight, the components they replaced aren't adjusted correctly, probably the tie rod ends. This is because the dealer's mechanic didn't do a thorough job or they're trying to rip you off.
Dealers make their money through repairs, not the sale of cars. Only take your truck to the dealer for warranty repairs or recalls. Find a respectable shop for any other repairs.
My naive friend took his car into the dealer for a minor repair. He got a call from them about the cooling system fluid being green, that it needed to be flushed and replaced. Of course he said go ahead and do it, so he ended up getting a new water pump, hoses, belt and new fluid, which is or course... green. I think it cost him $800 for "repairs" not related to the original problem.