Possible Torque Steer in Chev Truck

I have a 2002 Chev 1500HD. It has a 6.0l and rear locking differential. For the most part the truck is stock, other that the slightly larger tires (285/75/16). When I'm in 4wd and accelerate hard the truck wants to pull to the right. If I accelerate normally it does not pull. This only happens in four wheel drive. 2wd is straight as an arrow under hard acceleration. I brought it to a dealer and they said that it is cause by the torsion bars being tightened out of spec. They are that way so the larger tires don't rub on the fender. They also said that they tried out two new trucks on the lot and they pulled like mine. My feeling is that dealer didn't have a clue. I brought it to a different dealer and they feel that it is normal torque steer. I've had several other people try this on their trucks, which are much like mine, and they didn't have any pulling. I can't find anything on the internet about this being normal on a truck. Any logical advise would be much appreciated.