no tail lights
Simple. You have dash (instrument) lamps? If so, that means the tail section of the headlight switch is getting power. If so there is one wire from the headlight switch ---through the kick panel connector---to the rear harness to the rear
You are working on a 73? Go download a shop manual, free, here:
http://www.forabodiesonly.com/mopar/showthread.php?p=1970088617
and more here, and also some simplified diagrams
http://www.mymopar.com/index.php?pid=31
If you do NOT have instrument lamps, first thing to do is get into the fuse panel and check the tail fuse.