Very interesting. The washer is identical to the one I have (a rebadged Hitachi), except mine's in white of course, and this one appears to have a plastic tub! I never knew they made them like this. The tub on mine is porcelain, but with a plastic balance ring at the top...the second (later) design. From what I understand the tubs in the early models from the 60's were completely porcelain, balance ring and all. The cycles were more limited, however.
Mine is a 1977 model, so with the plastic tub, it could put this one around the early-80's, perhaps?