Door skin removal (72 Duster)

greg340 had the best info.
I looked at a wrecked door I have, and the top appears to simply hang. There were a couple of welds near the top.
Production body shops would grind the edges off of the door of the door that is getting the new skin. then the folded over lip could be easily removed. As for getting the salvage skin off the donor door(assuming that you are throwing away the rest), you could chisel around the inside(or use a cut off tool) making sure you don't bang into or cut through the skin you're saving(cut into the door parallel to the skin). Then trim the leftover metal. You could gently bend one of the "new" skin edges and put over the original door frame.