hemi70se
It looks like you and I are out on a limb alone on this. Until someone can come up with photos from the 70's showing the vent was just left open I'm going to rely on the two magazine articles I can produce to show it wasn't.

I went back and reread the two articles thinking that maybe they were the same car. They were not. One of the cars had 3:91's and the other has 3:55's. The articles were 2 months apart and two different cars.