Most likely the guy who converted the bus was a plumber or had a plumber friend that knew how to solder brass pipe. They did it right with rubber hoses to isolate vibration. There is nothing wrong with using copper, iron (not galvanized, sometimes the tin will flake off), exhaust pipe, aluminum, plastic, or like a car 100% rubber based hoses that can both stand heat and oil products. As long as the pipe doesn't leak, crack or flake foreign material into the cooling system, use it! Good Luck, TomC
