|from Standard Oil of New Jersey photograph|
It turns out that it is part of a group of 1,000 cars built by MDT in 1926-1927 and 1928 and assigned to series 53000-53499, Lot 540-B and 53500-53999, Lot 572-B, respectively. They had end doors, as shown above, plus 10' door openings and a cubic capacity of 3,544 feet. By the time of this photo, the car above had been renumbered into the series 196500-196999, a transition started for this series of cars in 1941 (the other series was renumbered into 196000-196499 at the same time).
For both types of cars, there were additional renumberings and conversions to box cars and plating of the end doors in the 1950s. As I develop my CAD capabilities, I will put this end door car, with its distinctive corrugation, on my to-do list. It's unusual and there were 2,000 cars with this end door design, making it less of an oddball car.