I need to add wiring for a trailer hitch. I have seen many kits, and done several searches. I haven't found something I really like.

I am looking for a good trailer hitch wiring harness. Preferably, one with the full tail section already connected. I.e. I am looking for a tail wiring harness with a trailer wiring harness already connected. Does something like this exist? If so, what is a good one?

 

FORD Vehicle Specific Kit (hopkinstowingsolutions.com) I used these. No cutting factory wiring. Unless you have trailer special there is no way to plug in a 7 pin connector, and that is not plug and play either. The 4 pin T worked great for me.

 

Etrailer.com has everything you need. Fast ship, good prices and large selection. As stated above if you desire a common 7 pin RV flat plug which accommodates a brake controller, you have to order the controller and run 2 additional wires from cab to the rear, one for the brake controller signal and one for 12V+ for breakaway battery charging .....Oh and a 3rd if you want a reverse light signal on trailer. If you just need park, turn signal, and brake lights all you need is the 4 Pin T and a flat 4 pin trailer connector.
The 4 pin T plug as shown in link above is easiest to use even if you do need to run the additional wires for brakes as it prevents cutting and splicing the harness.