Magnum Truck Racks Modular Wiring Harness for Sierra and Silverado with Light Model 56004Magnum Truck Racks Modular Wiring Harness for Sierra and Silverado with Light Model 56004 When you need an easy solution to install your lighted headache rack, our modular plug n play wire harnesses by Magnum are designed for an easy install. These wire harnesses run under the bed, plugging into your truck's body harness. The plug and play design virtually eliminates the need for any wiring knowledge, giving you a simple solution to power the LED