i'm starting to wonder if i'm missing some things from a/c and fresh air venting. i'll try and get some pics later. we're doing a frame off on 73 convt. w a/c. there is no plenum flapper in the upper cowl per aim, i've seen used ones for sale advertised to be for 68 and up. this car was wrecked and repaired (crappy attempt at repaired) on the right side. we pulled front clip and firewall to access rusty cage for repair. only thing inside there is the door at lower kick panel and a vacumn valve attached to it (inside car). should it have more, it's a base model car.