Where to find a heater control valve

My 65 dart has the push button control for factory A/C which has two vacuum lines to the heater control valve. I'm guessing that is to be able to control the flow of water in order to adjust the A/C temperature. The valve has a double diaphragm so it can pull from either side. I have seen these but can't locate one now that I need one. Anyone know where I can find this item?
Tom

EBAY