It's actually the shifter lock out cable. You can't shift out of park unless the key is in the on position. Kind of a built in security system so somebody can't jump in your car and shift it into neutral and roll the car away and onto a trailer or tow it away rolling. This mechanism was on the AOD 87-93 cars.It attaches to the steering column, by the key. It prevents you from being able to remove the key when the shifter is not in park. The older models had the button on the underside of the column you would push to remove the key.