It features ribs that end maybe 2 feet from the side of the car with a flat piece reaching the side of the B&O M-15 boxcar with a door that  opens to the left.  It is seen in front of the partially shown tank car at the bottom of the photo, a little to the right of the center:

https://www.shorpy.com/node/25497?size=_original#caption 

Gary Laakso

Northwest of Mike Brock