The "Description" and "Application" section show this as not fitting the Mustang. This is misleading because this will work just fine for the 68 Mustang with a little modification. Since the door panel on the Cougar is much bigger than the Mustang, just put the original Mustang barrier on top of this Cougar barrier and trace around it with a pencil. Trace the holes for the arm rest, door release handle, window crank and remote mirror knob. Get some scissors and cut the excess. You now have a perfect vapor barrier for your Mustang. The Mustang suppliers don't carry this item.