I was about to pass on this one but then I realized I might be looking at the remains of an old popular Celebrity.

Sterling Rail - Flat Car Bridges For Sale

That flatcar there, KCS #1245, appears to have both a very low number (for any piece of rolling stock) and further feel like it came right out of an old Athearn box.  I'd think it's a 40 or 50' flat (other pictures show it is marked #36 54 on the end, so that likely means it is 54 feet long).  I'd reckon it was a piece of MOW before meeting this end.  Maybe it will indeed be a noble bridge somewhere soon.