Here's my take on the towing package. According to this media blurb from ford:
The towing package consists of the hitch, the wiring harness, and sway control, whatever that means. There is no mention of transmission coolers or different final drive ratios.
Now, to dig a little further. I have the Ford Workshop Manual for 2013, so I looked at the wiring diagrams for all the modules. There isn't a sway control module. But what I did find was that the Ford wiring harness that seems expensive at about $65 is actually a module that communicates with the Body Control Module when installed, using the CAN bus of the vehicle.
The wiring harness adapter is operated from the CAN messages from the Body Control module to control the turn signals and running lights. The brakes
are triggered directly from the brake line.
I suspect that the Body Control Module knows when the trailer lighting
adapter is installed as it communicates via the CAN bus. My theory is that the trailer adapter communicates when the trailer lights are connected (easy to identify), and the Body Control Module can then activate the sway control that's likely built into all the vehicles. It doesn't make any sense to look for trailer sway if there isn't a trailer connected.
Wiring Harness #DT4Z-15A416-A
Trailer Sway Control works with AdvanceTracŪ with RSCŪ (Roll Stability Control™) using a yaw motion sensor to monitor the motions of the truck to detect trailer sway. When sway is detected, the system works to apply selected brakes
and/or reduce engine power to help the driver regain control