Hey again,
I checked my PCM connectors today and the connectors on mine are brown. I read up somewhere (excuse me if i'm quoting the wrong person) that if you have brown connectors your vehicle is already equipped with what's needed to handle the 8spd?
Since I don't have a 2014+, I can only use some background experience to speculate and make some assumptions.
If you pull the dash console, and can find an 8-pin connector that is unused near where the rotary shifter is located; that likely means your dash harness is ready. Then, if you are able to go under the truck, and find a large round connector near the transmission taped to a wiring harness, you're PCM harness is likely ready.
If you don't have those connectors, then I would assume (key word....assume), that you would need to source the right harnesses, and then just plug them into the brown connector on your PCM.
Then, I assume (another key word...assume), you would need to use HP Tuners to activate the 8HP70 option in your PCM and deactivate the 65RFE option. Its a simple dropdown selection - I could show you what it looks like in a 2012 if you want via screenshot. I'd assume (key word again) that it would be the same in a 2014.
Sorry I can't help more, the whole 2014+ Brown/White plug is beyond my experience.