if the truck isn't a factory cab light truck i doubt there will be any harness for the lights, but if you have an overhead console you can get a factory harness that plugs right in. The lights are not hard to position, under the headliner there are knockouts (holes) in the roof support structure for the factory lights, i reccomend using a holesaw that just fits inside the hole and use that to make your pilot hole, then go from the outside in with a unibit to make the hole for the light itself, put some masking tape around where you'll be drilling to minimize paint chipping. as far as an easy way to drop the headliner, my suggestion is just take it out, unbolt everything that goes on it and pull it out, more work but better than messing it up.