Have you had any luck with those radio delete plugs for the doors/cab?
I have 2 of these on hand: 15965867 - Genuine GM PLUG, Side Door OpeningNo. The part number I found indicating the door harness plugs turned out to be the smaller generic door plugs for accessing the exterior handle bolts or similar.I might have one more option for looking up a part number, but not sure if that will have better results.