I love my 1979 300SD and intend to get a early 1980's 300D to go with it, but can we agree that the ventilation systems on these cars are junk? Has anyone had success converting their "automatic" (i.e. worthless) system to manual? Believing that form should follow function, why shouldn't I go to the junk yard, get the controls from any old Dodge Dart and shove them into the part of my dashboard that now contains a series of worthless buttons and a temperature dial?