Lionel 6151-12 Pyro Seat - The 6151-12 Pyro seat is used on the radar truck, twin gun truck and the search light truck. Much has been written about special markings including the use of numbers embedded in Pyro's products. This is a misnomer that the pundits have issued for years, most likely to further their own egos. Pyro mold makers did use number in some items, but well after the mold had been run thousands of times. These mold marks are used by mold makers to identify parts in a mold where many of the same pieces are molded at the same time. If you were molding 4 seats at each shot, and one showed a tiny defect, how would find that defect unless you hid a mold mark somewhere on the item. Common sense folks!