does your dash have round chrome vents in the shape of ball. new for 1968 in Gm vehicles, flow thru vents instead of vent windows and kick panel vents.

As explained by my Grandfather back in the Enerson years, Astro Ventilation utilized the already engineered air conditioning dash vents on all Pontiac or all GM cars from 68 on, without airconditioning. If you fired up the vehicle, the heater fan (when controls were placed to "vent") would come on low, and stay on, as long as the car was running, and blow fresh air from the firewall/cowl inlet thru those A/C vents. If you open your front doors, you will see a black grill on eather side, this I believe was your exhaust or method to de-pressurize the car's interior. Just another means of "flow-thru-ventilation".

Great idea as my folks were chain-smokers back in the day, and I remember them getting a 72 Impala with Astro Ventilation and it was a relief to the lungs, eyes, and clothes being able to exhaust some of those fumes! No money for A/C back then.......but money for those Mark Ten's!

I'm going down to the archives now and see if I can find a write up on that feature.

Yeah for sure, one of the most indelible memories i have of the old 66 four door Parisienne was choking in the back with my 2 brothers ( I always seemed  to have to sit on the driveshaft hump too!) while both my parents smoked away in the front while listening to the gravel beat the crap out of the underneath of the car at the same time as listening to CFCW (country favorites of yesterday and today!)   We had set all the presets on the radio to CHED but that didn't stop my dad.

No astro ventilation on that one!

Funny how it works.  Both of my parents smoked for a least 50 years and they're around.  It's  probably the 2nd hand smoke that gets you eh?