Original 72 Door Panels?? Exterior Screw?

[72restorationvirgin]

Ok so I got some original black door panels from a member and I mounted them. The PO drilled holes in the blue door panels that were originally on my truck in all four corners for stainless screws... I"m assuming the PO didn't want to get the plastic tabs.... Those panels which are also original w/ stainless trim/scrolls don't have the one exterior screw mount on the side that the black ones do.

So were the blue ones for a different year or for a different trim? Both panels are original so I don't understand. The black ones mount up perfect, tight and I don't see the need for the screw. But I'm thinking I might have to drill another hole in my door so I don't just have a blank hole in my door panel. Thoughts anyone??? I attached a pic of the black panel.