To keep this concise: DO NO EDIT NONUS VEHICLES using the editor at all. Don't touch it.
Explanation:
For some reason editing any Nonus vehicles breakes core files of the game. I don't know how the editor affects modded vehicles but I made it so any engine can fit in any vehicle EXCEPT NONUS in my game and and it has been working still. There's occassionaly crashes but i've had those even when playing the game without mods.