I searched a lot for info very specific information but couldn't find everything I needed so I figured I would do my best to help.
If you have a 2015-2017 Crew cab and have purchased the Kicker subwoofer kit second hand this is what you are looking for.



First off I have a 2016 Crew cab with the pre run C pillar (308A group) speaker connector that works with the Kicker kit you can get from Ford's website. I simply wanted to use this just so I didn't have to mess with running cables and splicing into the factory stereo and all that.
There are 2 versions you can order. From what I read the versions after 2018+ wouldn't work correctly with the pre run C pillar cable. From what I tested this is only true with enabling the 7 speaker Crew Cab with Kicker sub option in Forscan. (I'll explain more later)

My biggest issue was finding the little cable that goes from the pre run C pillar to the amp on the Kicker sub enclosure. Luckily I was able to get it from my for dealership after speaking directly with Kicker. Kicker said they cannot sell it directly to a customer, so it must be ordered by the dealership.

If you need this, call your Ford dealership and tell them you need part number #FL3Z-14A411-H
Here is their system search path as well in case they have trouble finding it:
Ford > LIGHT TRUCK (L) > 2016 > F-150 2015-2020 (FC) > 4 - Electrical > 1503 - Speakers > 05D - Speakers, Radio Subwoofer B, Crew Cab, Super Cab; 20/OCT/2014-22/OCT/2020 > Part #FL3Z-14A411-H > Wire Assy




My cable took 4 days to arrive at the dealership. It was $120 ( Kicker said MSRP is $37.50 but I think these are getting really hard to find).


Now the easy part is actually installing the cable and subwoofer. There are guides already how to peel back the weather striping and plastic on the C pillar to ensure you have the pre run connection. This cable connects there and then to the subwoofer. Just look in the audio section. There is a great guide for installing aftermarket subs using a harness you can get on amazon.

My Kicker subwoofer came out of a 2020 F150 that did NOT have the pre run C pillar so the cable I got was for running all the way to the stereo and battery. This is why I had to order the cable.
Here is my sub box part number:


Once I had the sub installed in my truck with my new short cable, I had to enable this in Forscan. Otherwise the sub won't do anything.
I tried the setting that is actually designed for this enabling this which is listed as Crew Cab 7 speaker with Kicker sub ( or something like that) but this didn't work.
I then enabled the axillary subwoofer setting and this works perfect.
I had heard the other setting actually didn't sound very good anyway so I am happy with the result.

So in short, if you can get a good deal on a used Kicker sub kit made for your F150, it will work from what I did. All in I have about $400 into it. Really, you can get the Kicker hideaway kit and the Amazon harness and it will probably be cheaper. I just wanted a more oem look to mine.