Then its probably a more modern version, either the push feed or the "Classic". I am not certain who makes a replacement sight off the top of my head, but I believe there are a couple of places catering to this. A search would probably yeild better results than I can.

Also, there is NECG that makes a universal island that requires filing and soldering. Their insert may or may not work with whatever mounting base Winchester is using on his model's sight. Their website is here .