The S-Helper Service models were based on the Union Metal Products Co.'s pressed-steel panel-sided two-bay hopper cars. These were rated at 55 tons.
The NYC rebuilt 1,500 cars to have the extra carrying capacity of the side-panel hoppers. Both the PRR and the New Haven only rebuilt one such car. Other railroads, such as the Wabash, Frisco, and the CN rebuilt literally thousands of cars.
(source: NASG Dispatch, April 2003 issue)
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