It looks to be a 36’ car, probably 8’6” inside height or less. Not many roads used that style of side truss, most had the diagonals going the other direction. The high letter boards and lack of lower board for reporting marks eliminates a lot of roads. Also the door design, the horizontal slats and lack of a X bracing also eliminates a lot of cars. The extra wide center slat hints at a double deck, as does the door design. It could have the split doors seen on some double deck cars.
It looks similar to a Mather car or possible a GATC design. Mather did not have many 36’ stockcars, B&O with 16 and MCSX (a Mather reporting mark) had 25 in 1945 down to 9 in 1951.
Looking through my photos shows the following roads had high letter boards without lower boards CNW, CMO, NP, & Mather. But almost all had a visible X bracing across the door.
