Part of the Astro Ventilation system. There were also exhaust
vents in the door jams on mine. Had a 69 Caprice & 73 Impala
with it. Neither had AC. Kept the car quite cool......
Also had a 67 Impala wagon with comfortron AC. IIRC it did not
have Asrto but used ball vents & lap coolers.
73 Zeno
LFOD !