As post 12 states, later M-B used this same system of vacuum-switched coolant valve. Klima kits those parts, if you want to stay M-B. I guess that M-B doesn't make such parts, just brands them, so not important to me.

Re post 9 questions (sorry, just saw this):

The ebay listing didn't specify applications. They were selling a bunch, so likely a liquidator who got them from say a trucking incident sell-off or bankruptcy. The PN is in the photos if that helps. In my 1964 Valiant and 1965 Dart, I did similar, using a small plastic valve off ebay listed for ~2010 Ford, only $8 also from a liquidator, but I had to fab a metal bracket.

I did test the valve with a hand vacuum pump, just to insure the diaphragm didn't leak. As I recall, it sort-of popped open, similar to the way the door lock actuators in our cars do, though those are push-pull vacuum instead of working against a spring.

It would likely work on the supply side of the heater core. I say this because in my 1960's Chrysler cars, the two heater hoses run parallel from the front of the engine to the firewall. With factory AC, one was run over to a coolant valve on the inner fender. But since their taps on the engine are close together, as are the two heater core tubes, I am sure many people mixed up the hoses. I've never heard of the valve failing due a mix-up. Perhaps even the factory workers mixed them up (Billy-Bob on graveyard shift).

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans