Depending on what you get,most aftermarket lights ground through their own body at the mounting bolt.You might have to run a ground wire from the light mount back to a good,clean,paint free point on the frame,especially in the back,because of the rubber mounted fender. BTW,my 04 has [had] individual ground wires at every light,that were all ganged into one wire at the plug in connectors.MOST of the time,lighting problems trace back to the ground. Some 60grit sandpaper and a nice jagged star washer can be your friend.
