the light dont do jack for you. if your backblading or using a rear blower your not looking at that dash till you hit the bottom of the drive or if your realy lucky about half way when you notice the resistance. buzzer+gear ftw. it would be easy to do on my kioti. there is a little gromit? that covers the shift lever hole. put 2 contacts 1 at f&r then put the other contact on the gromit so that when its moved out of neutral it will hit one of those points. you could also do it so once the neutral contact is broken the lack of a path causes a beep.