Maintenance of Way: 2-Bay Open Hopper
Reference
This plain-vanilla 2-bay offset-side open hopper is of unknown origin. It was in use as a ballast car at least into the mid-1970s; here it's seen with American crane #11 and 65-ton switcher #7079:
Nelson Tower
...and with SW1 #400:
Nelson Tower
The Model
This is a no-brainer.