I dont know anything about that particular truck, but it sounds like you have a center diff unloading. Basically as you accelerate, the weight of the truck transfers towards the rear wheels and the lighter easier to spin front tires recieve all the power from the motor. If the truck has a center diff remove it and fill it with about 50K diff fluid. That should solve the problem, yes in extreme cases you will see the front spinning faster than the rear but that if the point of the center diff it makes the truck steer better. You will also notice the truck accellerates much harder.