I ordered this wiring harness from etrailer.com "Hopkins Custom Fit Vehicle Wiring for the 2012 3500 by Ram" code number 41157. I just unplugged my rear 7-pin harness and plugged this into the existing wiring and ran the cable to the location I wanted in the bed, drilled a 2 1/8 inch hole and installed the receptacle. The harness is about 8 feet long. Pretty easy. As you can see I have a 2014 and this 2012 wiring harness worked with no problems.