RBBB circus 1948
Yes. I was real surprised when I was able to purchase a copy of
Bandwagon magazine, a publication by Circus Historical Society, January - February 2002 issue, to learn that many of the first cars owned and operated by the circus were former WWI Army hospital cars that, like the steel cars that replaced them after WWII, were adapted to house cars. There are four articles by the late Robert S. MacDougall that cover RBBB cars from 1919 - the 1990s, with the first article also touching on the open-platform coaches that saw use before the wood hospital cars were acquired, including some that resembled the NS coach mentioned above. I can't deny an interest in wood vestibuled cars since in my modeling era some would still be around in MofW service... but this is a straying a little bit from the subject, which is about heavyweight cars.
In addition to the January - February 2002 issue the November - December 1999 issue deals with the former WWII Army hospital cars, January - Bebruary 2001 issue dealt with coach histories between 1957 and 1972 (covering not only the Army car use but also the early lightweight cars that were purchased, while the last article in the series, September - October 2004, deals with the first 25 years of the
Blue Train. For any interested in the circus train's history or passenger cars in general I highly recommend these articles.