I agree with John, though the '72 Lady Ks seem to have been pretty prolific as well, being available from late 1971 until early 1974, when replaced by the large capacity 1974 model. The 1966 Lady may hold the record for having the most "offspring" or similar but not exact models that came around from 1967 to 1971.
I may be one of the most fervent 1970s/1980s Kenmore black panel fans on this site, but I can see John's point about the Lady K no longer capturing the glamour and pizzaz if you will, that they once had. The black panel Ladies offered a lot of stuff that I would never use. Yes indeed, the electronic machines were cool in their own right, but I am more of a BOL fan than TOL.
I think the 1963 Lady K, just as John said, wasn't overloaded with features, it was, in my opinion, incredibly attractive, and functional. Some of the future models, though full of interesting features, would have gone largely unappreciated in my house because we have always been happy with two speeds, more than 3 water levels, and a normal and delicate cycle. That's all I ever use, and I don't use the low speed very often.
I just took delivery today of a 1963 Lady K washer in Coppertone. It came out of its original installation from a Philadelphia home. Since I have a matching dryer, this could be cool! The washer needs some work, so I'll be enjoying that this year.
Gordon