G3GM 1973 to 1977 A-bodys. Chevelles, Monte Carlos, El Caminos, Laguna, 442, Cutlass, Malibu, GTO, LeMans, Century, Regal, Grand Am, Grand Prix, Sprint, Gran Sport, Can Am, Hurst-olds, and other 73-77 A-bodies
Here's a setup I pulled off a '75 Cutlass Salon 2-dr. The Olds version doesn't have the rotary dial...but, instead has the slide bar across the temp control. Never did get any interest in the heater-a/c box and think I finally just threw it out.
The auto position is dictated by the slide bar on the bottom. The smaller flex tube has an air inlet screen that mounts on top of the dash and the air that is circulated down through that is sent down to the box controls/sensor and the temp is regulated. I sold this dash temp control to a guy who needed one for his Cutlass Comfortron.