Door Plastic
7demon2 I believe he is refering to the upper door panel. On your 72 its the upper metal part of the door but in the late 70's they change it to plastic ala federal safety standards.
Problem Child, as of now no one that I know of offer those. My dad has the same problem with his 75. We will probaly use older model doors and aluminium in the back. Most junkers are in the same shape as yours so boneyards are out of the question. Good luck at finding them the only other chance is NOS.