PCC Body Design Patent ~ Monday, June 08, 2009
It is US Patent 110,384 "Design for a Rail Car or Similar", invented by Dan H. Bell, assigned to the Transit Reseach Corporation.
I hadn't realized that the body design itself was patented (though I have heard that Brill was forced to pay royalties for their look-alike Brilliners).
Searches for Transit Research Corporation lead to other interesting patents. Enjoy!