My 67, #1317 had the cutouts when I bought it in CA 1977. However, it was missing the trim.
I bought NOS GT trim hardware and there were three screws already mounted on the back side
which fitted perfectly in the three hoes in the rear valance. Cut off the bottom part and put them on
the car. No drilling required through the top of the trim.
Could it be that Ford changed this part and went from two screws to three. My car was ready at Ford
1/31/67 and at SA 5/25/67.
Texas Swede