Quote:

Your car has A/C. Mine doesn't. The non A/C cars didn't have anything there. The A/C cars obviously did. The shape of the inlet is completely different on an non A/C car.



I concur.

We are all aware the AC boxes have that square foam piece between the box and vents. I'll probably duplicate something like that and add it to my non A/C heater box resto kits. I'm sure a numbers guy will bust my chops that his car never had one though

Still gonna make em and add em. But like mentioned above, might have been a reason like some venturi effect to draw in cabin air? Probably not though. Those old duct halves were stapled together and leaked like a sieve. I actually work for a company that makes space age type equipment to darn near hermetically seal duct halves together now a days. In fact I'm in Alabama working on such a machine for a Mercedes supplies - working through Thanksgiving while everyone one else thats not too scared to tell "the man" to pound sand spends Thanksgiving with thier families.