I recently bought a 70 Cougar as a father/son project. What I need to know is this-the front rocker extension panel on the passenger side is only about half there. On Mustangs Unlimited website, and others I have looked at, they only advertise that part for 65-68's. Is there that much of a difference between the 65-68 and the 69-70 pieces and if so what is it?