Heater Control Valve needed

Anybody know where a guy could find an OEM heater control valve for a '73 Dart Sport 340 with A/C? This is the gold plated valve that mounts to the passenger side fender well. It controls flow from the heater hoses to the heater core. I've checked around, and this thing is dang tough to find (even aftermarket versions)!

Thanks in advance for your help.