[68 TT]

Originally Posted by drewskiren

No, that was added to GM Cars and Trucks in the 60's sometime - as an exit for air that comes through the cowl/HVAC system. It would help with defogging the glass primarily. I think these trucks got them in 72? They called it Astro Ventilation back in the day. Think of a vacuum cleaner, if you plug the exhaust side it won't suck very well. This large exhaust vent just allowed more fresh air to flow through the system, through the cab, and to the outside. If you had fumes in the truck, certainly this would help to clear them, but that was just a side benefit.

It is a great idea to add the vents to your truck. It will make the HVAC system work better. I planned on putting them into my truck too.

You should get some of the reproduction Astro Ventilation decals for the side glass like was put on my 68 Camaro. Simple small white script lettering with no background. It would add just a subtle touch not many would notice.

http://www.rickscamaros.com/camaro-a...ecal-1968.html