Mid-1980s. I have the matching dryer in daily use, one I took in trade and repaired many years ago. Just changed the felt ring last year.
I also have Amana washer, very similar to this SQ model, purchased new in 1991. Perforated tub. I have changed the motor once or twice, and the timer knob. I'm still amazed that I have not touched the pump at all. Newer (1970s) versions of Blackstone had a poor quality pump that had a tendency to swell and seize internally, so maybe I'm just assuming that a plastic pump should not last 20+ years.