The so-called "Merci" boxcars were sent by France to the USA as thanks for our assistance in World War II. As was noted above, there were a lot of small standard gauge four-wheel boxcars built in the US during World War II in kit form by the US Army Transportation Command for use in Europe. A few either stayed stateside or came back. Some, still in kit form wound up at Cass Scenic Railroad in West Virginia, where they were (are) used for storage. A scrap yard near my home in central Pennsylvania has a couple as well, as well as a double truck version. The one on eBay may be one of the World War II cars.