I figured since I rebuilt the non AC heater box, might as well give the left side air vent box a freshening up. Taking it out was easy enough, three 3/8' nuts holding it to the dash frame and a 1/4" retainer holding the vent cable.
The metal door that opens/closes to allow fresh air in is round. It has a 7/8" rubber gasket attached to it. My gasket looks good and is surprisingly pliable.
Since I have it out and will remove the rust from the door and repaint the whole unit, any thoughts on what to use on the rubber gasket to keep it pliable for the next 40 years?
Attached is a high-level diagram that a fellow member posted - thanks for the posts, very, very helpful.
