This brass freeze plug Set fits every Oldsmobile V8 engine produced from 1964-1984. GM installed steel freeze plugs originally because they are cheap, and the cars were intended to be used daily. When used infrequently, the corrosion inhibiter in your anti freeze gives up and the steel plugs will begin to rust and leak. Restorers in the know use the brass plugs as a preventative measure. They are hidden by the engine paint.