In my 1960 MC-2, I installed a bonafide 5 trumpet train horn (3 trumpets face forward, 2 face rear). It is an old tuned unit, hard to find anymore and many$$$. I put it in the spare tire compartment along with a dedicated extra air tank. Ran a cable system to the drivers seat to pull the valve. Had it in there for several of years but took it out to give the space over to a minisplit AC. Still light it up at midnight every New Years to wake up any sleepy neighbors.