What do you guys think this is from and is it 12 or 6 volts?
Auto Lite made lots of electrical stuff along with horns in the mid 1930's mostly supplied to larger cars, and lots of Chrysler products.
My guess is that horn is Plymouth, from the early 40's.
If it is Plymouth from the early 40's it is 6 volt positive ground.
Vibrator horn like that doesn't recognize polarity, don't worry about + or - ground.
David, do you know if it's 6volts? And if it is will it make sound with 12?
Can't tell, you might look inside the cover to see if there's a 6 or 12 v marking anywhere. IF it has an adjustment, and is 6 volts, it might be able to honk on 12 V. If it's a 12 V horn, it probably won't honk on 6 volts.