Climate Control Part ID, '78, 300D

I'm looking for the part name/number for the vacum operated heater control valve located in the engine compartment, passenger side, front. It's leaking at the bottom seam but still works fine. I'm trying to sell the car and wanted to know cost for negotiations. Hate to sell it but my wife refuses to drive the "Dirty Thing".

Thanks!

Bill,

I guess so. It has a squarish box on top with a bunch of vacuum lines going into it (9 actually) with 2 more into the bottom. It has two small(1/2") hoses, 2 in, 2 out. On the front it looks like one of the lines is coming from the circ pump. BTW, the box has a madi in the USA sticker on it.

Appreciate the help!

Thanks Bill! After my last post, I found an catalog that had a drawing of it. I almost passed out at the price $350!

Thanks for the help!!!