Modding out a unit

Edit: found a workaround for the Timur elephant artillery CTD, so no more help is needed: end of edit

I want to mod out elephant artillery due to the CTD that occurs from them. So what do ?I need to change and will it make a saved game with them in unplayable?

I decided it might be easier to make them all with no ammo, doing it through mymod and if doesnt work change them to arquebruiser.

So I got mymod set now the only question I have is where is (export_descr_unit.txt) suppose to go I tried putting it in the data folder but the game won't launch, if I remove it then the mod launches.

I also copied sound and world folder and put them in mymod

Edit: the game won't launch if you give a missile unit zero ammo so that won't work