1968 differs in the plugs that connect to the sequential unit. Correct for Cougars built after 1-2-67 with the stop lamp relay located under dash. XR7 and standard Cougars use the same rear wiring harness to the tail lights This is a grade "B" harness that may have minor sun damage, splices or other cosmetic defects. The 1157 taillight bulb sockets are sold separately.
*NOTE* Need help diagnosing a Cougar turn signal problem? Victor Yarberry is the world’s most knowledgeable expert on the subject. Vic has owned Cougars since the 1970's and is the designer of all of our solid state sequential systems. There is no question he cannot answer! Here is a link to a great source of information on the subject.