Yes, technically it has to be a new model. As I already said, no table hacks/re:textures. Also, it has to be textured and released(I think I broke that once or twice).
A couple more standards: not appearing in other sci-fi universes (for example taking the X-Wing, renaming it and saying it's from FreeSpace, or taking a ship you made for another sci-fi universe and transforming it into a FreeSpace ship).
You can go for revamping and older model, but that can go two ways: making an HTL model/better texturing and you add it to the old model page, or making something sort of a Mk 2 that has a new entry.
Appearing in a mission or a campaign is not important, but needs to be mentioned.
Also, please use the categories. I will help with that if you need help.
If you have any more questions, I stand at your service!
Also, is there anyone who has the Hades Combine materials or a very very large User Made ship collection on his hard drive who might let me take a 30 minute stroll through their computer via TeamViewer?