I have a Nov 66 shelby. It has the screws at the rear. It was a TSB that would have been applicable to any vehicle returning for door panel loosening, so the date of the TSB Isn't relevant. I can also tell you that if you do this, FOLLOW THE DIMENSIONS exactly, otherwise you'll miss the metal structure of the door.
As for the door panels, there are several different manufacturers. At least three that are all different. TMI, Dash Designs and Mustang Market are all different. I have seen them all before settling on the dash design door panels. The area the cups fit in were the biggest issue. TMI cut the vinyl incorrectly at the cup openings, Mustang Market panels are actually a bit short and the door handle cup would not fit.
It gets expensive returning them as well.
-Keith