I had a washer like this which was a 1973 model - in Avocado, that was part of trailer full that were stollen from me a few years back. That is one of the machines I would have enjoyed tinkering with.
These are 800 models. Hard to say for sure just how many models under the Lady K this is - it depends how many were active when these were made. Sears had the 800 that was patterned after the '66 Lady K just below the Lady K, then several 800s from '69, '72 and '73 all at the same time that looked similar to this one.
I have a money shot from the machine I had - I'll find it in the archives and post it here, though this machine could have a Roto-Swirl OR a Vari-Flex, we'd have to see the model number for sure.
Gordon