...Drawings 24, 24A, and 28. No specific dimensions are given for the vent location. Just position above the longeron and clear of the rudder pedal mounting blocks.
Thanks for the replies. Position is not an issue because the hole is already in the side skin but the drawing Vlad sent answers one of the questions I had. It shows an aluminum strip backing up the plastic vent. I was also wondering if there was a recommended number of rivets and their layout but I doubt that it's that critical.