This combo was released in 1957. I think it was 1959 or 60 when WP redesigned the combo from the ground up in a 29" cabinet. The Kenmore version of this 57 was very similar in size, but the controls were set back a bit on the top of the cabinet in a shape similar to the Lady Kenmore washer panel in Robert's collection.
We saw one of these 57 KM combos at a sale in Minneapolis a few years ago but it was in a basement and nearly impossible to pull up and out without injury to ourselves or the appliance.