As far as the 516-561 are concerned, how many of the boxes boasted the "Mark IV" (I cant quite remember the actual number off hand so excuse that.) name?

My AunTie Joey, when I was a kid always had Kirbys, at this time, pertaining to this instance, she had, has a 560, and had a Generation 3. She always bought all her Kirbys new, and I found out later on that she had two more I never knew about, one I saw only ONCE when I was a kid, and I am 100% it was a 516, 517, 518, or a 519, because it had the round belt lifter, and furthermore, it couldn't really have been anything older, because that wouldn't fit into the time period that AunTie Joey, and Uncle Forest were married. But, I asked her one time what others she had, and she referred to that one as a "Mark IV". Well when I became a collector I thought she was nuts, because the 500 series prior to the Sanitronic were not named.  Untill I started collecting more, and I saw one or two boxes with that name on it. That's why I am asking this question, to confirm if maybe she had a 516, or if even her 560 box could have said that.

and P.S. in the event the rest of you are wondering about the other past Kirby, since I mentioned there were two......just to sum it up, years and years later on a the last visit we made to their house, I saw a D50 sitting in their garage, she told me that she loaned it to a friend in need, for long term, she passed so it was finally returned, and upon it being returned it was saved for me. I was very surprised. Just like her other Kirbys, she bought it new in 1965, and it is dated '65.  So enough about that, just didn't want to keep anyone hanging. =)

I have seen long boxes with the names "Mark II" and "Mark III" before.