Here is a nice example of the Marx 4 wheel O gauge tin lithographed #20114 New York Central Pacemaker caboose.  This one has 4 diecast metal wheels on metal axles, and a plastic knuckle style front coupler.  This particular car is part of a series of 15 different numbers that exist for this car.  Collecting them all can be a challenge, and this is a pretty nice example.  Photos show the caboose from all 6 sides, with a penny in the shots for size reference.  Priced to sell, with only actual USPS Ground Advantage or Priority shipping cost charged!