Atlas produced the Trainman Line war emergency gondola in the PENNSYLVANIA scheme recently.
http://archive.atlasrr.com/ORS/arc-otm52gondola.htm
Atlas O Trainman 52' 6" gondola
http://archive.atlasrr.com/ORS/arc-otm526gondola.htm
You might be able to find a few at Atlas O dealers.
You could make a reservation for the next round of gondolas.
Andrew