Yes, known as Bays in most of the U.S. as well. Mine was a '69 built in October 1968 and shipped to Jacksonville, FL the end of that year.
I still cannot find any reference to an 18-window anywhere even using those search terms, nor can I visualize that arrangement based on how the others are set up. After 1964 there were no more corner windows so that gives you at most 21 and typically the skylights go if you drop a tier so that gives you 13 windows max. Where would those 5 windows go to make 18?
Someone asked about this on TheSamba.com forums as he was considering buying one from an ad (the seller insisted it was a factory-produced vehicle) and the answer he received was no as far as a factory production item was concerned. A link to an article or image of said vehicle went unanswered. My guess is there was no pic in the ad for him to post on the forum which makes me wonder why you would buy a car with no pics. But regardless, I am still unable to find a single reference to an 18-window microbus anywhere using three different search engines (Google, Brave, Bing).
My guess is the wait for such a kit will be longer than the wait for Trumpeter’s Devastator was; much longer.