On the outside wall, at the rear of the engine compartment, is a block connector for the rear lights. Below is the sequence of connections. I added the grounding lug. Normally, the ground wires would be attached directly to the two existing ground wires located in the bundle of wires going to the connector block.
When I converted mine to LED's which draw less amperage, I increased the number of brake lights from one on each side to three. With the standard lights, the brake light would only contain the wire from the one brake light.