The Pennsylvania Railroad class X26 is a wooden, externally-braced, single-sheathed, 40-foot box car built near the end of World War I. These cars could carry up to 100,000lbs (50 tons). The PRR had 9,900 of these wood-paneled cars. In the late 1940s 3,500 were rebuilt with steel side panels and reclassified as "X26c". In 1950 (my modeled era) there were still 5,500 X26 box cars left on the roster. By the 1940s most (if not all) photos show wooden doors replaced with a Youngstown-style corrugated doors. PRR cars seem to have retained the vertical brake staff. The car uses Andrews 50-ton freight car trucks. (photo: PRR #44824 from my personal collection)
This is a photo I took, in October 2012, of the Northern Pacific outside braced box car stored at the Galveston Railroad Museum in Galveston, TX. Why am I including this (and two other photos) in the PRR X26 topic? It is a very similar car, and what I liked about this particular car is that is clearly shows how such a car has weathered. I don't have any additional information about this particular car. Apparently the car is used as an outside office/storage space.
This section shows the side just to the left of the door.
This is a close-up of the lower, left-hand side of the car, showing both the truck and how the wood has deteriorated.
This photo came from the October 2003 edition of The Keystone Modeler. This photo is of a PRR GTC26. There were twenty of these cars who were X26 box cars that had their roofs removed so that they could be used as high-sided gondolas for coke transportation services. They were suitable only for use with coal-dumping machines. They were in use for about ten years starting in 1953. This would make for an interesting modeling project.