I noticed some weeks ago that my car wasn't showing the middle tail lights when I stepped the brakes and today I decided to open the plastics to check the problem. For my surprise it doesn't have any wire installation in there, or even wholes to those pass, the plastics where the bulbs would fit don't have any small holes to pass the cables.

Is this common on early FD's?

 

No its not common.

Wires should be there somewhere. Post some pics if you want more feedback.

 

Will post photos tomorrow but I removed the plastic and the full piece to check it. No wires going there at all.