As noted by Marshall, I used the = original ground wire to pull two new wires to the rear of our Westy. Our set-up is = a little different than most, as A/C vents take up the normal in dash = radio location, we installed our CD/radio on the headliner. I only had to run = wires from the top of the passenger door back. But I did = succesfully run other wires up from behind the dash through the drivers front pillar = to the space above the drivers door (the front speaker wires, power for the = radio, etc.).