You will most likely have to go to the dealership to see the parts diagram on their computers. Your car is old enough that it was not have full support on the online subaru parts sites. Those knobs were also used in the impreza coupe/sedan, and the legacy of the same era, as they secured the door to the jack stowage. They are just a dumb, slotted tab that doesn't lock into anything. A grocery bag will knock one off and punch it into the body. Check the junk yards. It was a common part to many cars.