This diagram (regarding rear lights) has little in common with the wiring I reconstructed in my Jan 1973 FJ40.
All of the rear side markers, running lights and license plate light were a solid green wire in my truck.
You may notice the diagram has no wires feeding the lamps in the rear combination lights.
In my case, the right rear combination light stop/blinker wire was green/yellow. The left rear was green/orange. It is my understanding that the left rear might be green/black.
Note that when I remade my rear wiring harness, it had green, green/yellow, green/orange, green/black, green/white, and red/lavender wires. It appeared to me that Toyota was preparing to change to the newer rear combination lamps (red/amber/white) and incorporated extra wire to allow the extra circuits for brake signals and directional signals to be separated.
If I were Irish Wake, I would dissect the wiring harness near the right rear corner of the harness, and check the signal for each of the wires to ground with a test lamp or multimeter. It would then become apparent which wires feed the lamps on the driver's side that don't light. A jumper harness could then be spliced in to feed the driver's side with the correct circuits, bypassing the mess hidden by the auxiliary tank. I would purchase 10 ft of each color coded wire and the necessary connectors from the Coolerman webstore, matching the jumper harness color codes to the wires feeding the jumper harness.