I went back and looked at the pictures I took when my upper dash was removed, and there were definitely foam seals between defroster duct and the metal dash top. They were attached to the defroster duct, and were a single strip at the back edge of each side (they didn't go all the way around the openings).
I was also looking at the 69 AIM online today and noticed that it calls out for seals between the defroster duct and the metal upper dash. They are different for each side, which seems strange.
So, is anybody installing these seals? If so, what are you using?