Since today is Saturday, I cannot ask my parts dudes if it is even available from OEM. But - if an internet search or calling your favorite Ford dealer comes up empty - you could purchase a trailer connector kit with a harness and repair the existing harness splicing in as far back and you need to find good wire Use good wiring and splicing tecniques ensuring weather tight splices. Whether you need a 4-pin, 7-pin or combination connector a little searching will do. Something like this: 7 Round - Blade Custom Fit Vehicle Wiring | etrailer.com

 

This guy poked holes in all these wires in countless places
There is green corrosion in most of the wires, starting fresh would be ideal.
I’m no stranger to wiring and just did the same thing you mentioned to my 06’ f250 the other week.
lots of salt on the roads where I live

 

A trailer wiring harness is a length of wire at the back of a vehicle that allows its electrical system to connect to a trailer. Integrated with the vehicle's existing wiring, it provides a standard connector, such as a 4-way flat plug.

 

Yep. And it also runs down the frame rail and plugs in beside the transfer case.
11 wires total- 7 for trailer and 4 for the truck taillights
Needing that entire length of wire/plug
Holes poked in wires everywhere there is no point in salvaging any of it
But thank you for posting a Wikipedia bio for trailer wire harness 🤣

 

Harness tags are on the harness convolute tubing, typically a white plastic adhesive tag wrapped onto it. if it is up there it would be several inches down. Then again it could be anywhere. If you do find it do not use anything harsher than water and gentle wiping to clean it as you might lose the numbers printed on it.