The Atomic Waste Disposal Car No. 6805 was available for two years beginning in 1958 and it represents one of the more unique items produced by Lionel during the Post War period.

Creation of this car resulted in major changes to the 6424-11 chassis casting. It is the only car in the 6511 series that has metal trucks that are attached directly to the chassis with clips instead of being riveted. It is also the only regular production car with metal trucks that has the number heat-stamped to the left of the WHITE serif lettered "LIONEL" inscription on the sides. These bar-end trucks are equipped with tabbed couplers.

With the truck plates retainers on the ends of the cars no longer needed, the body mold was altered to hold two sections of Super-O rail. This was done by creating "rail stops" at the end of this car to hold the rails in place. Additional slots in the chassis were created along the length of these rails to secure them to the chassis. One rail was wired to a center rail electrical pick-up on one truck, the other rail was wired to a special brass eyelet on the truck stop of the other truck to carry the current from the outside track rails. The electrical circuit that was created through these rails on the car powered the "RADIOACTIVE WASTE" canisters that used a No. 402-300 flashing lamp that illuminated the three RED warning lenses on the sides. The lettering on the sides of these canisters was RED "DANGER" and was underscored.

Other flat cars produced during the period that the No. 6805 was in production also have the rail stops at the chassis ends. See: No. 6424 Variation D.

The handles at the top of these canisters are frequently found broken or cracked.

There are three variations:

Variation A: LIGHT GRAY painted BLACK plastic canisters.

Variation B: TAN painted BLACK plastic canisters.

Variation C: There is no number on this car. It is believed to have originated in an uncataloged set, and it has GRAY canisters, and arch-bar trucks with one disc and one solid coupler.

MPC has reproduced the canisters but they are unpainted GRAY plastic, whereas the originals are painted BLACK plastic.