Place a block of wood between the jack and the body to raise it, then slip another block between the body and frame for safety after the body is lifted. Do this next to the front and rear bumper, and each corner of the cab, after loosening all body mount bolts. Slowly and carefully raise one side at a time, leave the other side loosely bolted on so the body doesn't shift, and constantly check that you don't pull on any wires, hoses or linkages. I used this method to replace my body mount bushings using only one floor jack and a couple of 4"x4"x12" wood blocks. The other method is get 4 to 5 strong peolpe to physically raise the body. I've used that method on pick-ups, since the bed and cab are separated. Remember that you may also have to extend the steering column/shaft, transmission and t-case shifter/linkage, unhook the gas filler neck, and cut the fan shroud.