It looks like the "smooth" side surface is not as smooth as a molded plastic surface nor a brass or plastic car side. So, my guess is that it is a Rowa car that has had its fluting sanded off and then painted silver. So, in shape, it looks very close to the B&O cars that were originally run with the First light weight "Columbian". But, those were painted blue and gray with gold striping, at least until Amtrak took over. And then they were painted other colors. I don't think they were ever silver.
The B&O also had some silver, fully-fluted dome cars with different (actually, unique) dome shapes that were originally made for the C&O, for a train that the C&O discontinued before ever running it. So, those domes, which have different slopes at the opposite ends, slanted glass in the inner dome panels and curved glass on the outer dome panels. So, this car does not have the proper sides, dome shape or window pattern to be those cars, which the B&O ran on the "Capitol Limited" and the "Shenandoah".
But, both of those cars eventually got retired and went private. So, one could use this one as a private car in a recent era.
