the Heater Delete option?

This is where the door and hinge separated. The hole in the hinge is from a rivet. I had to be real careful when drilling them out, this stuff is so fragile. Normally, there's a little tab/wing on the bottom and top edges of the door with holes. The hinge had angled tabs that fit into the door tabs and are fastened by rivets. The corrosion made the tabs weak. Not a very robust design to begin with though.
View attachment 1716206570

Here's the other one I have. The pic is from several years ago. This one is obviously made out of plastic. Like I mentioned in an earlier post, this one had a cable operated grille vent like a B body. At one point I took the grille off and actually made a door and hinge for it. It would have worked, I just didn't like the way it came out, especially the hinge. Maybe I will revisit it.

View attachment 1716206574

That's all I got.

Absolutly, pictures of original parts like this is always interesting and in my case also useful.
Thank you for taking the time.
And good close up pic is helpful when I want to mimic surface finish...
As for the cut out, the original ยด68 SS-cars use this very same vent box from what I have seen.