Ben mounting them anywhere as long as it's not next to an exhaust pipe. Never had a seconds trouble in 30 years. When not in the radiator, even on a 100 degree day, it's at least 80 degrees cooler than one in the radiator. Remember that these heat exchangers work backward in the winter and warm the fluid, something the external ones can't do so if your in frosty land you need to choose what's best. Here in the heat capitol that's not an issue. Also, plumb them in with fluid hose not fuel hose like so many do.
