[shelbert]

I wouldn't think the heater control or lack of it would be a problem if the flaps and ducts were all good but we are talking about a 40+ year old truck. If you wanted to you could just put a cutoff valve in the heater line and turn it off during the summer to prevent needing it. Then just run the under hood vacuum line just to the actuator.

As far as the actuators, I do not know if they are available still but I took one off a late 70s think a 78 square body at a pull a part ( some were plastic some were metal) I didn't trust the plastic one so I got a metal one. It will mount right up perfectly but the rod that pulls open the door will need to be used from your truck. The one of the 78 was much shorter.

Oh i forgot to mention if you dont use all 3 of the plugs on the A/C switch make sure the other is plugged well or you will get weak vacuum (although it will be hard to miss if its leaking it is very loud under there)