The rear wiring harness joins with the front-to-back harness on the right rear side, against the inner wheel well, with snap connectors.  Running lights are solid red.

For cars with separate turn lights,  Brake lights are Green with a Purple trace, Right turn is Green with a White trace and Left turn is Green with a Red trace.

For earlier cars with combined turn / stop lamps, Right turn/stop is White with a Brown trace and Left turn/stop is White with a Purple trace.

For cars with separate turn lamps (Like Jim's), the brake lamp snap connector is a "four way" connector with only three (Green/Purple)wires in it.  Put a bullet on the wire from your center lamp and plug it into the fourth hole.  Simple!

For cars with combined turn/stop lamps, you must go forward to the "Magic Mystery Box" (DB10 Relay Unit) and attach your wire to terminal 5, where the Green/purple stop lamp wire is.

On our '55 (Twin Spare) DHC we mounted a center stop lamp that I had originally bought for our Packard, which says "STOP" when lit up.  Barbara mounted it to a bracket held on by the "tire grabber" between the spares. It looks so proper that we did not even take it off for the Palos Verdes Concours (see picture in Sports Car International).