You should be able to pick up a "pigtail" from the Chevy dealer that will mate to a plug under the dash on the drivers side. It will have four or five wires that will connect to the brake controller. Take it with you when you buy the brake controller, a friendly and helpful RV tech might help you match up wires if you ask nicely, since you're buying the controller there. All you have to do is find the place to mount it, find the mate to the plug under the dash and plug it in.
Four Corners Unit