Trains Magazine has posted (behind subscriber-only content barriers) a roster of both the two current Ringling Bros. Barnum & Bailey circus trains and its stored parts reserve equipment on two separate PDF rosters:

http://trn.trains.com/en/Magazine/~/lin ... 1280E&_z=z

Although RBBX cars tend to get as thoroughly gutted and rebuilt as anything else out there, there still exist possibilities for preservationists. For example, I noticed that two sister cars to the B&O Museum's stainless B&O Slumbercoach Oriole are currently in the reserve sideline stored serviceable at Palmetto, Florida. If any panels or parts were needed for restoration, well.......

Most of the passenger cars in question are former UP and PRR, with a few stray N&W, SAL, GN, and B&O for good measure.

Actually, Trains is saying on their Facebook page that the rosters are accessible to all.........