Just real quick, one more time, without pulling my harness apart to verify, you should have 5 wires coming out of the tail lights-one probably black for the ground, 3 that probably go to the individual brake lights and one that probably goes to all 3 running lights. They will go into a 6 position plug that you are missing. On the car harness side, the 3 that go to individual lights are tied together probably about 8" from the plug, at least it feels like a splice there on my harness. The ground will go to the metal shield over the gas tank fill tube. If you don't have the ground wire, your lights will never work. The body shop may have not run that wire through the access hole, in which case you will have to remove the tail light panel to find it. If it is missing completely, it just screws to the back of the housings with a ring terminal, so you can build your own. I'll try to get time in the next few days to get you the actual wire colors or what goes where.
Steve