Lucky break. Electrical sensor.Remove old one, put the new one in it's place.-------------------------------On some cars, there is a short metal pin that fits into the tranny.grease it well and the friction of the grease will hold the pin in place, so you don't drop it as it goes back in.Some cars have a small gear (grease it well) and it will rotate as it goes back in.You will know the sensor is back in far enough when you can press the sensor flush against the tranny. Gasket should line up easily.I put a drop of loctite on the bolt's tip for the ones I fix at my place so the bolt won't work looseand it doesn't get overtight. -Bob