Here is a Marx Toys mechanical or windup plastic O gauge freight train set with its original box.  Although a "starter set" when released in the seventies, this was near the end of Marx train production, so finding nice boxed examples of these isn't always so easy anymore.  It is set #530.  The set consists of a gray plastic mechanically powered 0-4-0 steam engine (this one DOES work as you can see in the test video, and the key is included).  The tender is a gray Santa Fe with white lettering.  Then there is a yellow #131000 Seaboard Coast Line gondola with black lettering.  The final car is a red #1977 AT&SF (Santa Fe) caboose with white lettering.  All of the cars have the late one piece plastic wheel units, and tab and slot type couplers.  7 of the 8 sections of the gray plastic track are here and are unbroken.***  The original box is present, and other than one split corner and a small piece out of the side panel to the right of the cover, the box is pretty nice (neither of those are seen when displaying the front).  Photos show all of the items from all 6 sides with a yardstick in the pics for size reference.  Priced reasonably, with only actual shipping on the roughly 3 1/2 pound package charged to the winner (I do give you a number of shipping options, so you can pick what works best for you).