pu/panel body mounts are much different - panel frame doesn't have the riveted on cab mount pads, pu frame doesn't have panel mounts - also the front of a 58 frame is about 1½-2" longer than the 55-7 due to the gravel pan behind the bumper, and the panel rear extension is riveted on and vital to allow mounting a rear bumper on the panel - I'd really rather see you take the driveline/axles from the NAPCO and swap your stepside axles back on the panel so you don't waste a panel truck!!
Bill
