I feel like i'm missing something here and this is harder than it should be. Seiko has no parts search, the spare parts companies sell seiko case back gaskets but no list of which case codes they fit, it's juts a parts number.  I have a seiko with an 02W0 case code and after checking the like 9 pdfs in another thread here of case codes and parts i couldn't find that case code listed and no combination of google search terms really seems to turn up anything. No site seems to have the ability