[RahX]

Toe does not cause a pull, ever. If one wheel is off center and the other is straight | \ toe will center itself so both tires are / \ which will throw the steering wheel position off. Toe causes tire wear and determines steering wheel position. Bump steer is caused by improper steering geometry and caster. Have them check all of the angles, including thrust angle. If the front and rear wheels aren't in line like they're supposed to, when the front end loses traction the back end would likely push it one way or the other. I'd have to agree with the dragging rear brakes theory too. It wouldn't take much for the rear brakes to send the truck sliding. It has to be something dumb since it isn't a problem all of the time.