You are correct it most likely is a Chrysler unit, at least the one in our 1984 310 was. I believe if you look for a early to mid 80s unit you'll find what you need. I got ours off of eBay for about $25. You can also just take the control unit to a Chrysler dealer and they might be able to get one for you. I believe there is a part number on the unit itself somewhere.
This post http://www.airforums.com/forums/f159...ses-33272.html
has a copy of the vacuum diagram. It mostly matched mine with only minor differences. I spent several hours playing with the various vacuum lines making sure everything was working correctly.
The other thing to watch out for is vacuum leaks. Another reason our control didn't work was because someone plugged the vacuum line going up to the dash because of a cracked hose. That kept the vacuum gauge and the a/c controls from working. Took me a while to figure that one out!
Hope this helps.