1) Walthers FP7. One reason some railroads bought these engines was that they faced a tremendous seasonal volume of traffic - passenger, mail and express - around the holidays, say Nov 1 to Jan 30. They could buy E units and tie up scarce capital in locomotives not used most of the year or buy freight locomotives with steam generators and high speed gearing that could pitch in on the seasonal rush, but haul money-making freight the rest of the year. That's the reason the PRR - which had a huge seaonal volume - had 40 of the breed. Unfortunately, the release of the Walthers model shown in MR doesn't have the distinctive PRR "barrel tank" between the front truck and fuel tank, although earlier releases did. The review says the models will have prototype specific detail, so maybe the PRR version announced as part of the release does include that detail
https://i.pinimg.com/originals/3a/db/c6/3adbc6fcdb22c45987b917a2d298bc20.jpg
https://www.whiterosehobbies.com/products/walthers-proto-920-42519-ho-scale-emd-fp7-diesel-pennsylvania-prr-9867a-dcc-sound
2) Half empty hopper cars. Another such use of divided hoppers was to haul different sizes of coal from one mine to one consignee - but not every dealer could take or needed 55 tons of one size. Presumably the waybill stated what end (A or B - the end with the brakewheel) had what size. The CNJ painted a white stripe on the center side strake to designate such cars (I would think the ORER had that specified also, but its a lot easier to have it maked on the car)
Anthracite coal used for home heating purposes is uniformly sized to the following dimensions. The different sizes are used in different applications. The larger sizes consisting of stove, chestnut and pea are typically used in hand fired applications. Smaller sizes like rice, buckwheat and barley are typically used in automatic stokers where the coal is mechanically fed.