i dowloaded the SSJR_HopperPack_PotashCorp and followed the readme file to install it.
To Install:
-open the zip folder
-drop assets folder into your main Railworks folder
-it should not ask to overwrite anything.
now the potash corp Gunderson 4250 worked like i placed it on the track in my own route and it show up. but the potash corp Cylindrical Hopper it there in the car name list but when placing it on track there nothing.