same question as title...ive got a air tank and a hadley air horn off of a mack truck and i would like to put it on my truck.....also where do i find a air switch to trigger the horn?

I no longer use air horns - have recently switched to the finger.

Just get a 12v electric over air solenoid, plumb it to the tank with 1/4" air line and wire the solenoid to a momentary on switch in the dash. Or go back to that Mack and get the air valve.