First of all, if you buy something like this you must realize you may have to make modifications and deal with issues like leaks. If you have a stubborn leak, align the fitting where it needs to go, clean both surfaces, then use a two part epoxy and screw it in, let dry overnight and then install. Be sure you use an electrical source capable of supporting a motor. Use a momentary button for horn and mount it in an area that has enough room for freedom of movement, the under hood is not a hospitable place for anything.