does anybody happen to have a left rear fender for a 1970 Oldsmobile cutlass S.

 

Welcome to the site! The rear fenders are called quarter panels. Typically they have rust at the bottom caused from leaks around the rear windshield. Is that the condition of yours or is it accident damage? I've got a parts car that has damage just above the wheelwell opening but is solid at the bottom. I'm located in Medford Oregon. I know California is a big state, would you be close enough to check this out in person? If you need the complete panel reproductions are available. The quality is up for discussion as some people are happy with them but others find them difficult to use. John

 

the quarter panel is damaged from the rear windshield leaking like you mentioned. do you have a picture that I could see. I live near Monterey Bay.