Hemiallen,
I'm not exactly sure how this works, but I believe it connect to the factory harness. Check out
THIS page.
Part Number:
20111, Fifth Wheel Adapter Harness.
2000-2007 Dodge Ram Pickup Full Size Truck w/Factory 7-Way
You may have to drill a hole to mount it inside your bed or install it on an
L bracket, as Greg did with his.
Also, the
7' loop below can extend from your factory 7 pin connector, at the rear bumper, to your fifth wheel 7 pin wiring harness.