My Osborne electrical assembly manual is lacking definition on the page for the tail lights so I am asking you guys.
When taking my assemblies apart there is one nut underneath one of the stamp nuts. This is only on one of the studs. In the manual they reference a nut but I cant tell where it is in the drawing.
Which side of the car, and which stud? There is a "J" clip used to hold the wiring harness that is held in place on the outer, upper left side stud. There are also grounds for the back up lights on the outer lower studs on both sides.
If you look in the library section of this forum, you will find a subject titled - "Mustang Hardware Spreadsheet 64-66". It has about 3000 entries pertaining to hardware used on 64 to 66 Mustangs, all body styles, in two files, one by part number, the other by application. Browse away.
Jim