Here is a Marx O gauge plastic #51100 Southern auto carrier.  It is maroon with yellow lettering and has a gray plastic superstructure.  Has a nice load of 4 vehicles, but I believe that they are reproduction.  This version has 8 stamped metal wheels on metal axles, is equipped with plastic tilt couplers on both ends, and is on type G trucks, the style with the stamped steel truck frames.  The rack is the earlier type, from before they started reinforcing the corners on the ends (later ones the ends have a triangular strengthening area in the upper corners on the ends.  All of the little tabs are still there on the rack, as you can see in the pic with the rack off of the flat.  Also included a couple of shots of the vehicles off of the car, to show NO logos on them (although some actual Marx production cars also did not have the logos).  Lastly, PLEASE LOOK AT THE YELLOW VAN TO THE FAR RIGHT IN THE LAST PHOTO - YOU WILL SEE THAT THE FRONT WHEELSET IS ONLY IN ONE OF THE "HOLDERS" BECAUSE THE OTHER IS DAMAGED.   Still a very nice car, great addition to your Marx railroad or collection.  Photos from all 6 sides with a yardstick in most of the shots for size reference.  Priced reasonably, with only actual USPS Ground Advantage or Priority Mail shipping charged.