Saturday we were at a mall, and walking down the row of cars, I saw two cars with the gas cover open and the cap gone. And I think someone is siphoning gas. Being a '77, I don't have an option of a locking cap. The only ones I see are for pre-69 cars. I suppose I could get a pre-69 neck and the locking cap. But would that cap be vented? Any other options? Paul.