This thread got me remembering the restoration of my '71 roadster.  I had considered putting in factory-style A/C, so researched a bit.  I do remember that I have vacuum operated flaps from the passenger compartment into the well under the rear grills.  The tube goes to one of the two vacuum valves that are part of the heater controls.  The wells just have a hole in the bottom about 5/8" in diameter.  '68 to '70 roadsters had a tube out of the bottom of the well.

And I decided not to put in A/C.  Too much work and too crowded in a big block car.

Larry

My vents are now a finished item on my list. As I have found out thru this thread convertibles did not have any tubes coming out from the vents for drainage but just a small 5/8" hole. The vent on the drivers side of mine had been "chewed" by some mice at some time during its life to the size of about 2 inches. My repair this morning was to take a 3 inch square piece of pond liner with the rubber patch, cut the 5/8" hole in it and vulcanize it to the bottom. Worked great and now I can move on to installing the tank today.
Thanks for all the help with this information.
Rodney

I have replaced the drain tubes on our coupe a long time ago and at that time I ordered an extra  set from GM. Our 72 has air and astro vent. The interior side panels have to be removed the hose is clamped to a spout on the side of the plemium and the other end runs to the inside of the rear wheel well were is riveted to metal drain that is located on the outside of the wheel well. Page m108 in the 72 assembly manual. So to sum up the water from the plenium drains  into the wheel well. If this not what you are looking for I got to practise my typing. Garry

Garry, after many discussions with other convertible owners we have found that convertibles dont have tubes on them, just holes in the bottom corners. Guess we  got cheated on water drainage as vert owners!!
I have to say your car looks awesome! Something to be very proud of!
Rodney