The Pipe Flat Car No. 6511 was introduced in 1953 and was the first of this type of flat car that was made. It would go on to have the most varieties of any car that Lionel produced throughout its history. All of these cars have the mold number 6511-2 in raised numerals on the bottom. No other flat car of this type would bear this number until 1956 when Lionel introduced the No. 6424-11 mold.

All of these cars were heat-stamped "LIONEL" in serif letters and the number was imprinted to the right side. Came with 13 No. 2411-4 side stake posts to hold the load in envelope No. 6511-17 that is illustrated below right.

The load was five plastic SILVER pipes that today are frequently found to have cracks along their length.

Better quality reproduction pipes are thicker and a different color that hold up better than the originals. Lionel made these pipes available for separate sale under the No. 6511-24.

This flat car was produced with stamped steel truck mounting plates on Type 6511-2 Die 1B bodies. Originally blackened die-castings, these plates show rivet detail on the top. The trucks were mounted to these plates that wrapped around the car ends and were secured to the chassis with screws. The trucks that were used were bar-end, and later issues would have tabbed couplers. Also see: Pipe Flat Car No. 6311. There are five variations:

Variation A: BLACK chassis that is painted BRICK RED and has die-cast truck mounting end plates.

Variation B: Identical to Variation A except the chassis is painted a DARKER RED color.

Variation C: The chassis is painted a DARKER RED color and the truck mounting plates are blackened stamped steel that do not show rivet detail on top.

Variation D: Identical to Variation C except used an unpainted CHOCOLATE BROWN chassis and is occasionally found with a gloss finish.

Variation E: Identical to Variation C except used an unpainted RED BROWN chassis.