This is a repaint of DTG GP40-2Pack01 (Train Simulator: GP40-2 Loco Pack Add-On) into Maryland Midland livery.
Now with the plows repainted and with new numbers like the real ones.
In order for this model to work, you need to already have DTG GP40-2Pack01.

Installation
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1- Open the zip archive, find the Assets folder, drag it to your Railworks folder. Answer "Yes" to the prompt about merging the Assets folders.
2- Drill down to DTG\GP40-2Pack01\RailVehicles\Diesel\GP40-2\NS\Engine folder. If the GP40-2Pack01 folder is empty except for a file named "GP40-2Pack01Assets.ap", open this file (it's just a zip archive) and continue drilling down until you find the folder.
3- Copy the GP40-2_NS.GeoPcDx file to your Assets\DTG\GP40-2Pack01\RailVehicles\Diesel\GP40-2\MML\Engine folder.
4- Now to see your engine from inside the cab you need to copy and edit the following GeoPcDx file.
  - Go to DTG/GP40-2Pack01/RailVehicles/CabView folder. Copy EXTERIOR_NS.GeoPcDx and paste it at the same location. Rename it to "EXTERIOR_MML.GeoPcDx"  and open it with TS-Tools. The file should be displayed in the "RW_Tools Editor" window.
  - Now open the editor's Search window (Ctrl-F), type "\GP40-2\ns\" in the upper field, type "\GP40-2\MML\" in the lower window, and hit the "Replace All" button. This will change all twelve occurences of this string. Close the Search window.
  - Finally save your changes (Ctrl-S) and close TS-Tools.
 
To use in a scenario
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In the scenario editor, enable content from DTG/GP40-2Pack01.
Now you should see the GP40-2 MML Units along with other units from the DTG DLC.
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I want to thank Chacal for his precious help!