AUSMHLY,
If you use halogen bulbs, either side can be tied to ground, polarity doesn't matter. I cut two pieces of wire about 18 inches long. Stripped the insulation and tinned the ends with solder. This stiffens them up so you can cram the ends into the back of the sockets. The sockets also have a couple of strain relief holes, so just feed the wire in from the front direction into the strain releif holes, bend the wire ends far enough to go all the way into the connector, then pull the excess wire tight from the front. Mix up a thimble full of epoxy and put a dab on top of the wires where they go into the back of the connector. After it dries, bend the wires toward the back of the socket around the strain releif holes. Strip the other ends of the wires. On the ground wire( just pick one, it doesn't matter electrically), attach one of those round electrical connectors. On the other wire, strip it back and solder on one of those lucas wire end connectors. Now all you do is loosen the nut on the back of your tail light where the ground wire should be from your tail/stop/turn light assembly. Slip the round electrical connector over the stud of the tail light. Make certain you have a star washer against the body, then the ground wire from the light assembly, then your new ground wire, then put the nut back on...Now find where the white with (brown one side, purple the other) connects to your tail/stop/turn assembly. These connectors are around 8 inches of wire away from the light assemblies on either side of the boot. Unplug and remove the single lucas connector and replace it with a double connector. Now you can add in your new wire for a total of three wires plugged into this new connector. One position will be empty. Once you seat all three wires into the connector, run a couple of wraps of electrical tape around the ends of the connector. This will help hold all three wires in the connector and exclude foreign objects from ever touching or shorting the wires to ground.