Daylighttrain among others have released skinned and modded versions of the Auran big boy. For a long time (and probably still is) there was a link in one of Daylighttrain's posts to his reskin of the Auran big boy into 4014. I believe it is fair game but definitely be sure before you release it... as we've seen recently, it's better to be safe then sorry.
Here is my take on this. If it is listed as the author being Auran, then you may clone, reskin or otherwise alter the asset if you own a copy of Trainz that is compatible. You may then redistribute it via the Trainz DLS for free for others to use. You may then, through the Trainz TCCP, include it in a payware Trainz route.
Any other use, distribution or otherwise is prohibited.
Just because N3V (Auran is just a legacy domain name) includes something as a built-in item and it may be listed as Auran in CM doesn't give you the right to do anything except what is allowed in the config.txt file. N3V is granted the right to include items from the DLS in payware or future versions of Trainz. That is a limited right that is NOT transferable under copyright law. The original creator retains all other rights unless stated otherwise. Just because another user may or may not have been granted permission does not mean you can assume you have permission. An author grants a publisher the right to publish their book in exchange for royalties. Buying the book does not grant the buyer any right to say make a movie from the book without reaching an agreement with the author for the movie rights.
If you're doing the older lower poly models from the earlier versions of Trainz (e.g. Trainz/UTC/TRS2006 era SD40-2, Class 37,etc.) and uploading them to the DLS for free, you should be fine.
