Kenlandrum,
There is an inlet, (cooling/O2) I believe, on the left side front of the suit where the cooling air enters the suit across from the regulator. It looks very similar to an Apollo era fitting only with out the "dogs". Most often this fitting has an elbow attached, and is capped to keep out debris. On the inside the fitting has perforations to allow airflow into the suit.
Being a draftsman (semi retired) I started to do a 2d drawing of same, for conversion to 3d later. However I am not happy trying to scale the pictures I have found on the internet, and both NASA and David-Clark have not responded to my queries for information.
So my best plan thus far is to take one of your fittings (which I love by the way) and sand it down for height and remove the remaining dog material then drill out the perforations on the inner surface. (Not the most accurate, but it woud give a good representation at any rate.)
Best regards,
Chuck