Need to get a fastner into a bolt hole with stripped threads or one in sheet metal or plastic where a nut can't be used for some reason? For $2, you can get a *well nut* from Home Depot. You'll find them in the hardware isle in the little clear plastic bins. It's a rubber plug with a machine screw through it and metal washers at both ends. There are various sizes, you'll want 1/2" for a oilpan drain bolt for example. You stick it into the stripped hole, and tighten it, which contracts the washers together and makes the rubber plug bulge in the middle until it seals the hole. They're very effective if there's any thread at all left; the rubber conforms into all the little grooves with the grip-o-death. Highly vibration resistent. A good choice for an unstressed area where normal fastners vibrate loose, like the horn mounting bracket.