Go to this directory
C:\Program Files (x86)\Steam\steamapps\common\RailWorks\Assets\DTM\ALCo FA1-PRR
Locate the file ALCo FA1-PRRAssets.ap and unzip it
copy the contents of the folder ALCo FA1-PRRAssets
paste them here C:\Program Files (x86)\Steam\steamapps\common\RailWorks\Assets\DTM\ALCo FA1-PRR
navigate to C:\Program Files (x86)\Steam\steamapps\common\RailWorks\Assets\DTM\ALCo FA1-PRR\RailVehicles\Diesel
paste my dcsv in the Engine and EngineFA2 folders the file FA-1_PRR_numbers goes in the Engine Folder and FA2_Numbers goes in the EngineFA2 folder
click yes for both files when asked
you're done