Pilot model 2384.1 before correction.

Although typically described as ballast cars, these diminutive prototypes (approximately 34 feet over the striker plates) are appropriate for far ranging uses in various railroad services. Ballast cars during the appropriate seasons, a substantial number of railroads employed these cars in a variety of services. In addition to their ballast carrying duties, many of these cars were employed in coal service while the same cars also were used in sugar beet service and, as well, in grain service. Being modeled by Challenger as part of this project, the Union Pacific Railroad had a covered version bearing a strong resemblance to early versions of ACF built covered hoppers. Not previously seen in model form, these cars are comfortable operating alone or as a block of cars in a consist. Typically fine Challenger detailing includes separately applied brass chain for all hopper door actuating mechanisms. 
Factory painted and decorated. Multiple road numbers. Each version is railroad particular. 

Pilot model 2388.1 before correction.

2384.1 Chicago Burlington and Quincy Class HK-50-4 two hopper doors each side. 
2385.1 Chicago Burlington and Quincy Class HK-50-3 single long hopper door each side. 
2386.1 Union Pacific Railroad Class HK-50-4 two hopper doors each side. 
2387.1 Union Pacific ballast car covered and modified for grain service. 
2388.1 Chicago & Northwestern Class HK-50-3 single long hopper door each side. 
2389.1 Soo Line Class HK-50-4 two hopper doors each side. 
2390.1 Monon Class HK-50-4 two hopper doors each side.
2422.1 (New Version) Chesapeake & Ohio Class HK-50-3 single long hopper door each side.
2423.1 (New Version) DM&IR Class HK-50-4 two hopper doors each side.