In the late 1950s, Marx sold a flatcar, labeled #5545 and lettered for the CB&Q (Chicago, Burlington & Quincy), with a large black clip in the middle. Marx shipped it with a pair of miniature trailers. These frequently got separated from the flatcar, so frequently you’ll find the car, sans vehicles, in the cheapie boxes at train stores and under the tables at train shows. The trailers are worth considerably more than the flatcar alone.
But there are some common, relatively inexpensive toys that work well on these common plastic freight cars.
David Farquhar is a computer security professional, entrepreneur, and author. He started his career as a part-time computer technician in 1994, worked his way up to system administrator by 1997, and has specialized in vulnerability management since 2013. He invests in real estate on the side and his hobbies include O gauge trains, baseball cards, and retro computers and video games. A University of Missouri graduate, he holds CISSP and Security+ certifications. He lives in St. Louis with his family.