Before I forget, thanks to Subtalk member Grounded Shoe Beam, R-10 #3210 was a Westinghouse-equipped unit through and through to the end of its service life. So, please make that minor correction in that R-10 car list that you printed for yourself awhile back.
From the stories I had heard and read (particularly from a New York Times article from that year), and it is still not clear if they are accurate or confirmed, #1575 may have been involved in a wreck somewhere along on Central Park West in 1946. It is probably the only known information I can possibly recall right now at this moment.
#1575 did, of course, later become the R-10 prototype car, and it would later displayed to the general public at Hudson Terminal on July 9, 1947, and at 34th Street-6th Avenue on July 10, 1947. You might say that was the very first post-W.W.II car design to be introduced for the NYC Transit System.
However, on a similiar topic, for years there was a mystery of R-10 car #3047 having an R-16 front storm door, and how it received it. Simple, that car was involved in a collision with R-15 car #5962 at 207th Street Yard in the fall of 1974, but #3047 was repaired and returned back into service in the spring of 1975 (with that storm door).
-William A. Padron
["Wash. Hts.-207th St."]