Main loom comes out of the inside of the chassis rail on the drivers side rear, some goes up to the rear cluster and the rest crosses over the rear crossmember - held in place by three clips. The remains of the wiring goes to the passenger side rear light cluster. There is a multi-plug on top of the chassis rail near the floor support on the passenger side which is the connection for the fuel sender.The only place you could effectively tap into the wires is where the wiring is exposed along the rear crossmember or before it enters the chassis inside the engine bay.
Les.