Changing SC unit attack sounds (model?)

I have a map that uses both the Marine model AND a firebat model based off the marine. I've changed the bullets on the firebat to fire (long story, don't ask). However, now I would like to know how to change the reference sound that the firebat uses for his attack sound. I know the sounds for the gun fire are the same as the gyroplane fire. However, I can't simply change the internal sound cause I want the marine to retain the machinegun noise. Bottomline, is there somewhere in the firebat model that changes the sound used for the attack? Changing the stuff in the Object Editor doesn't work, already tried it.