It's a Federal PA300, no doubt about that. The airhorn is very distinctive. Putting on a Federal is a lot less expensive than a regular air horn, compressor, and an air tank. What I'm confused about is why he didn't just use the airhorn function. Combining the two will only confuse traffic since they don't expect an emergency vehicle to be on the ROW. I'm assuming this happened in Arkansas, which may have different laws about sirens. In California, only authorized emergency vehicles are allowed to have sirens. I'm pretty sure that tractor didn't qualify as an authorized emergency vehicle. He would have gotten a citation if I was at that crossing and the laws are the same in Arkansas as in California.