Have you verified the loss of a ground at the light sockets? How about the connections behind the sockets or the connectors to the taillights? This stuff does happen and it is possible for a wire to be broken internally without being seperated from the outside and may appear ok. Just give a light tug on each wire to make sure. Check there before ripping the rest of the truck apart first. Be sure and verify the operation of your testlight or meter to ground when you check for power. The ground wire from the harness should be near the taillight in the rear. From MFG's standpoint it cost more money to run a wire back to the front than to ground it near the load (Taillight). Keep checking it's gotta be there somewhere. Hope this helps
