Recommend a horn for my dually?

A neighbor in AZ had a set of horns off of a locomotive. Not the horns that I have that are being pedaled as train horns but the real deal. He did have them on a truck but after several tickets he removed them. He blasted them for me once. A quick 2 second blast emptied a 15 gallon air tank. Ears were ringing for days.......I offered him $500 for them but he would not sell them....