Nascar Tool Trailer found at a flea market.  It is all-metal with spring-loaded handle, two wheels at rear, opening doors, four sets of rubber Goodyear racing tires with labels on the tires, and four adjustable jack stands.  The one here has one jack that is broken (1/2 of the part is there) and possibly it is missing the front caster wheels for the handle.  Not sure if this item came from a set or not.