If I understand this correctly...
Only 3 wires for each rear door are needed to operate the rear windows?
These wires are added to the X7 connector at the BCM.
These 6 wires did not exist in the X7 connector to begin with?
So I just have to strip my DL8 harnesses down to 3 wires in the connector and plug one end into the rear door plugs in the lower kick panels and run the other ends into the X7 connector?
Will my rear windows work at this point or will the BCM need to be programmed first?

 

You can try sending him a private message. No guaranty he will respond.

 

I'm at the last step of finishing this conversion on my truck before going to the dealer.
I have the front harnesses replaced, switches and mirrors installed, and working.
Also have the uplevel BCM.
Working on modifying the harnesses for the rear windows to work.
Just wanted a verification before I proceeded.

It would be best for everyone trying this to have a response posted in this thread.
I'm going to do what I think is the correct process whether he responds or doesn't.

I will share what I've done to get this working on my truck in more detail with pics once completed to make this more simple for people with non-DL3 optioned truck to get this done.

 

Follow the above steps exactly to the T step for step.

Once the BCM is programmed to a uplevel VIN the rear windows will operate properly if it's a new un programmed bcm. If you flash the new uplevel bcm to your VIN the rear windows and front windows will not work. You will also need to flash the stock radio to the new VIN or it will display locked and no longer work. It's best to find a uplevel truck the same year as yours if you have factory audio to keep the radio working. Either way you will loose the XM until you buy a new tuner and install. The XM tuners are vinlocked one time and cannot be reprogrammed. These day's the easiest route is to find a truck get the bcm and XM tuner from it if you want to retain xm. The other plus is windows will work instantly if it's out of an uplevel truck. You can then use a tech 2 to read the bcm vin to reprogram the existing radio.

I'm still here I just lurk mostly until someone genuinely needs help.

 

I finally did get this working recently.
I had to replace both front door harnesses and front door panels as the DL3 switches are wider and longer then my non-DL3 switches were.
I bought a used set of DL3 switches that were already programmed and with the new harnesses the power folding mirrors worked right off the bat with working signals.
I did loose the ability to lock/ unlock all doors and roll down the rear windows and when leaving the truck I had to open and close my rear door to get the RAP to turn off.

I pulled a used BCM and XM tuner from a uplevel truck from a junk yard and recorded the vin of the donor.
Took the the BCM X7 connector also with as much wire as I could grab.
I Installed the used BCM and XM tuner just for ***** and giggles and to my surprise the front / rear windows, front / back doors, window and locks worked.
Truck started and ran just fine.
I had to use my old drivers door harness to wire the rear windows from the BCM X7 connector to the X500 and X501 plugs.
I have an aftermarket touchscreen radio (Dynavin N7Pro) that picked up the replacement XM Tuner no problem.
The only things that aren't working now is the dome lights don't come on when opening the front doors.
My compass, air bags, and the rear park assist aren't working.

My rear park assist wasn't working before hand because I bought the newer style harness and sensors to go with the newer style Step bumper.
I rewired the new harness to the original connectors but for some reason the park assist isn't working.
Haven't figured it out yet. I'm not sure if the newer sensors need 12v where the originals I think might be 8v.
I did buy a new park assist module and installed it but won't be able to figure out the rear park assist till I get the truck programmed.

Took me a long time to figure this all out with a ton of help from this thread.
Tracking down all the parts and figuring that last few details with the wiring was the most difficult and frustrating part.

 

The park assist module is a one time vin locked module for some weird assed reason. You gotta buy a new module and program it it to new vin or go ****** module from the donor and it ll work if you want park assist.

Or my preferred method for those who don't like all the BS damm nannys see below.

The module is located under the passenger seat beside the outboard seat rail mounted to the floor towards the front of the seat track. If you disconnect the battery then unplug the module reconnect the battery and start the truck the instrument cluster will not look for the park assist anymore and quit displaying the annoying messages. There is a module in the center of the seat mounted to the floor do not disconnect that module. That module is the gyrometer for the stabilitrack system.