The die-cast metal three-bay, open-top hoppers need to be made out of lighter aluminum, so they can be placed anywhere in the train without having couplers in front of the hoppers being stretched and popped open from the weight.
The O scale die-cast aluminum three-bay open-top hoppers need to be produced in schemes for the
Chessie System
B&O, C&O, WM
the SOO LINE
THE ROCK
Andrew