I have 1978 Chrysler NY with the Air Temp that freezes up and want to change it out for a 1972 Chrysler manual heat/ac unit. Will this fit or need more modifications than worth the effort. Or, Are there a few years of manual boxes that do fit.
Welcome to Allpar. When you say 'freezes up', do you mean with ice? Or are the air doors mechanically binding, preventing the air going where you want?
1972 would be a different car. 1974-1978 C or Y-body (Gran Fury, Royal Monaco, Newport, NYer and Imperial) would have the same dash.
Some low/mid-line Dodges, Plymouths or Newports would have manual system (if you could find one), but that would entail the dash coming out for replacement.
Have you tried diagnosing the AirTemp issue to fix what you have? Is this an AirTemp II?
Do you have the service manuals?