This is a long shot. From my notes: the harness ID tag was wrapped around the end of the harness near the right hand tail light. There were four harnesses listed in the 65, two for hardtop or convertibles, and two for Fastbacks. One each from each group was with backup light provisions, one without ("C5ZB-14405-E" HT/CV w/o; "-F" HT/CW with; "-J" FB w/o; "-K" FB with).
The is a possibility that later in the production year, Ford eliminated the harnesses with-out back-up light provisions and went to the harnesses with the provisions to reduce inventory levels.
Jim