My favorite aunt had this dryer in gas and a Highlander washer with a flip switch for hot or warm water. I don't remember a water level selector switch. It was a sudsaver model and to keep the water from cooling too much, she never left the laundry room once she started washing; guess it's not hard to guess that the washer replaced a Maytag Master which she kept and used from time to time until the pump needed repair. Only the last load was given enough time to dry completely in that slow gas dryer; other loads were hauled out when the washer shut off and put on lines in the basement to finish drying in the winter. The dryer vent had its own little storm window to prevent cold air from falling in through the vent.
She told me that the dryer drum had to be recoated at some point; don't think they did a hot zinc dip to the drum. I wonder what they would have used to coat it in the early 70s.