In Toledo in 1938, on the eve of World War II, there was developed a new vehicle which became a symbol of the United States during the war and afterward--the Jeep. This little four wheel drive, off-road vehicle served as transportation for countless G.I.s and remains a part of the American road through its name and concept even today.

The first Pennsy round roof boxcars, the X-31, were built with internal racks to store automobiles. The 10' IH design of the round roof used effectively all the space under the freight car clearance diagram of the day. The acceptance of the first round roofs effectively broke the height barrier of North American boxcars, making 10' IH the new norm. But only 6 years later, the 10' IH was obsolete for auto loading. In 1939, the Pennsy needed a taller boxcar to cope with the increased size of autos. The new Jeeps, being developed as part of the modest military build-up prior to World War II, needed transporting, just like autos. So the Pennsy returned 690 X- 31s to their shops for rebuilding, a roof lift, if you will. To gain an added 6" in height a turtleback roof was adapted to the X-31s. The new roof created one of the most unusual cars in U.S. railroad history, the X-31F, the 81200-81889 series of auto cars. The increased height over 90% of the car was rather ungainly in appearance, but effective. Like its cousin the X- 31, the X-31F got auto car lettering. The lettering was notably more complex on the auto cars than the companion general revenue cars. X-31Fs were assigned to specific loading locations, such as Toledo and Catonsville, outside Baltimore. "Automobile" was stenciled above the road on the right side. The right hand door got a white stripe and square below to indicate auto racks.

The increase in height maintained the utility of the X-31Fs even into the modern era. Some had auto racks removed, though they might remain in auto parts service.

The kit contains urethane castings of the major parts-- including the unique turtleback roof and new running boards-- appropriate commercial detail parts and crisp decals. Kit includes the Prototype Data Sheet and extensive instructions. The majority of X-31Fs used the new Sunshine 2D-F8 Pennsy trucks. Some X-31Fs received National Type B trucks--2D- F13.