I have had my 66 Beaumont apart for a long time and I can not remember how the tail light wiring went through to the trunk.
Hopefully you can see by the pics what I mean. The inner bulb wiring I am OK with, the outer bulb wiring comes through from below and I can't remember how it gets into the trunk area, unless my body man filled the hole!
Just off to soccer. If you don't get an answer tonight, I'll try to get some trunk pictures tomorrow if you think it will help?
__________________
"So when you spot violence, or bigotry, or intolerance or fear or just garden-variety hatred or ignorance, just look it in the eye and think... The good outnumber you, and we always will." Patton Oswalt
I believe that wire just drops down and goes through a hole in the trunkfloor drop-off panel. At the very rear of it. The hole there is fairly large, about 1" diameter. The wire should have a rubber plug on it to fill this hole. Then the wire just continues up between the rear quarter panel and the trunk-floor. (the long little half-inch gap). Nothing really fancy there. The end of the wire should have a plastic clip on the end of it which clips into the wire heading up along the underside of the quarter-panel/trunk lid lip. Hope that all makes sense. Peter