Here's how I did it on a RKC.
I used lights #68977-00 which are double filament front lights and used brackets to mount them to the fender strut in the pre threaded holes on the rear of the RKC. The wiring can be run through the strut itself to the under seat area for hookup. I wired the blue of the light to the orange of the harness under the seat that goes to the rear lights which is the running lights. The purple of the light gets wired to the red/yellow in the same harness which is the brake lights. This gives you running and brake lights in the same housing. Hook up the two black ground wires from both lights and you are in business.
Blue wire = Running lights
Purple wire = Brake light (brighter filament)
Black wire = Ground
You now have running and nice bright brake lights because the lenses in these lights are unfluted red plastic lenses and the lights themselves which were originally standard equipment on a deuce have a double filament 1157 bulb.
I picked up some stainless steel plates from a boating supply store ( 3" X 1") enlarged the 3/8" holes that were already in the brackets to 5/16" to match the threaded holes in the fender struts and had to be reshape the brackets a bit in a slight "S" to move the lights closer to the fender and out from behind the lip on the bag. I took them to the buffing wheel and and with a little effort, they look like chrome and blend right in.
It was worth every dollar and any effort to do it this way. The lights are much brighter than the module lights and they are independent of the directionals for more visibility in the rear.
I prefer this method of adding lights as opposed to the equalizer and LED lights. The equalizer units being a resistor in theory to give you running lights and brake lights on a single filament bulb operate very hot and have been known to live a shortened life.
These are the type of lights I used and switched to red lenses.
Here's a finished pic of the lights.
Linear Mode
