Nothing official that we know of, but unless someone was practicing their Photoshop skills, we
do have not one, but two photos that don't lie - and logically how would they have covered the ever-building RR for almost five years with just four cabeese? They had to have done something. It doesn't look like anything the South Park had, it does have those B&S box features, and there is the precedent of converting other cars (the first four from J&S) to much needed cabeese. And since the official caboose numbering scheme apparently progressed directly from 1-4 for the converted J&S-built cars to the 5-88 for the Grande-built cars, I'd guess that any converted boxes probably retained their 10xx numbers, were not listed on the roster as cabeese since they were a temporary solution (and not particularly attractive), and with the 5-and-up cars coming online in 1876 were probably sent to shed duty or scrapped without fanfare by the time the Class 9 flats came about in 1880 and occupied that number series. I'm sure there will be quite a few people who will scoff at this apparently new discovery of their existence, but you have, as they say, 'the pictures to prove it.'