You must have the PC passenger car directory available from the PCRRHS (running a freight only line is not a good enough excuse!). At the merger there were 257 former troop sleepers listed in 9200-9499. 103 were still listed in the March 1971 passenger register. So they lasted quite a while although I don't recall seeing any photos of them in revenue or MOW service. How they were painted during the few years they still ran I have no idea.
Last night while browsing the shelves at the LHS, I found one of these Walthers express boxcars that was rebuilt from an old WWII troop sleeper:
I thought it was an interesting model, but my layout has no passenger service. (Not by my choice, the PRR killed it off several years earlier.) However, I know that a lot of old passenger equipment ended up in MOW service.
Which begs my question: were these troop sleepers ever used in MOW service on Penn Central? Or were they even still around by the time of the merger? Just curious if anyone has any information on these cars. I'd figure I'd ask before I spend $20 on one. :)