Dave's was an earlier build than mine. His quarter panels were different, with stamped indents so that the marker was semi-flush. Mine just had two holes. The marker was actually a Cougar part.
"Officially" the made the change on 2/15/1968, but I find is hard to believe that all three body styles and all three plants switched over on the same day.
Fun fact: The Revell fastback has the earlier marker which is correct if you build it as the Cobra Jet drag car. All of the "street" Cobra Jet GTs were built after the changeover, so they should have the Cougar marker.