I don't know what to tell you then, other than the pics show the obvious differences. Did it originally have a plastic liner or cardboard? I would guess that a pic of both of those glovebox openings would be revealing.
Probably cardboard on the '74. There wasn't much of anything left. But like I said, it's the same as the '71. Nothing to screw a liner to, just like the '71. Only difference is the style of the glove box hook. When I'm not on my phone I'll post you some beautiful pictures of how the '71 Dart and '74 duster have identical openings, and how I have plastic liners in both of them. All you need is a handful of screw clips.
