Hi
Thank you for your effort to make something new, I am super excited to participate in it...
regarding your issue, I had the same problem when I had UH-60 and A-4 mod installed, some mods make you not hear the tank engine.
make sure your saved games is clean from mods and try again, thanks.
Also I would like to offer my assistance with your project since I really want pvp ground battles get alive.
Thanks