Most I've seen have aluminum panels everywhere, but then I have seen some with everything gutted and removed, large holes drilled in the door framings, ect... to get as much wieght out of the truck as possible. that way they can hang as much wieght as they can up front. Although I have seen many have weights hanging behind the cab aswell. All weights up front isn't always best. Just depends on how hard the back wheels hook up and try to lift the fronts off the ground along with the engine torquing the frame up aswell.