Originally Posted by cubiculus
Yes, that fog lamp exists. Imprezas with this rear bumper and the rear fog light were available only in a few countries, for example in Israel.
Here is the link for the Impreza that is just being dismanlted for the spare sparts. According to those pictures, the fog lamp that you are looking for is still on that car. Try to contact that eBay seller for more info. Good luck!
The picture of the headlight stalk in that auction shows one that does not have the rear fog setting. Could be a picture of a stalk from a different car, but I would make sure that car has a rear fog...