Air Duct Identification

Now I'm trying to reassemble it.

I'm guessing there's some type of manifold that attaches to the bracketed opening, and attaches to the arrowed screw hole. The RH Air Ball Duct attached to the "Glove Compartment" panel comes right up to the side of this opening.
Does someone have a picture/GM# of this missing duct piece? I scoured the '73 AIM with no joy.
Greatly appreciated.
Steve







