Atlas HO 20006378 Chemplex ACF 5250 Covered Hopper #77Atlas HO 20006378 Chemplex ACF 5250 Covered Hopper #77 Part Number: 843069186243 Description Atlas HO 20006378 Chemplex ACF 5250 Covered Hopper #77 ACF introduced the 5250 cubic foot size covered hopper in 1964, and has since built nearly 20,000 cars. Most of the cars were equipped with pneumatic outlets and eight 20" round hatches for use in transporting plastic pellets. In addition to the plastics cars, a number have been built or converted with