You have the door harnesses, window regulators, and power lock actuators in the parts hoard. You might also join
https://67-72chevytrucks.com/ There are write ups on the window install.
The tailgate wiring harness is run under the truck and attached to the frame to the stock location you should see the loose ends on the driverside rear frame rail and in the engine compartment to the drive side of the steering column. I think the tailgate harness is also in the parts hoard but I never found the tailgate regulator.
I have the very hard to find Door Panels for power window and locks and the Kick Panels for A/C without the vent pulls available, it took me forever to find the correct ones for Milverado!
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