The Detroit & Mackinac Quad Hopper Car No. 6736 was produced from 1960 until 1962, and has a RED painted body with WHITE heat-stamped lettering and "Mackinac Mac" herald, center brace, but no covers. Came with early AAR trucks that have disc couplers.
The box pictured above has the number 6736-1 over-printed on a No. 6436-1 Orange Display Box End. This box, like most of the other over-printed boxes, was most likely sold in a set. Lionel rarely, if ever, offered over-printed boxes for separate sale. There are two variations:
Variation A: As listed above.
Variation B: Due to a fault in the heat-stamp die this variation has a WHITE "blotch" of paint on the face of "Mackinac Mac." This is a common factory error that is even illustrated in the 1961 catalog.