For the 98+, it should be coiled up above the parking brake pedal if I remember correctly. I can't remember exactly, but I think you'll have a thick red wire that runs out near the B+ post on the underhood fuse box, a wire that goes to the brake switch, and the blue wire out to the rear of the truck. The rest of the wires will be tucked up into/onto the cross member at the back of the frame.