There were 1968 800 models that were very similar. The one that has the same features as these has the Roto Flex agitator. There is another version of the 68 model that has the Vari-Flex, but IIRC on that one the smaller knob is a water level control, not a speed selector.
These are 1966 800 models actually which may have continued into 1967. Without looking at the stock number on this set here, which as you know is the best way to tell when these were built, an indicator would be whether the Super Roto Swirl agitator is plastic or bakelite. If it is bakelite, then these were built in 1966. If it is plastic, then these are 67 built. That was the only year the SRS was plastic and black.
Have a good one,
James