They do make a locking cap (old school)?that is available at most auto supply stores for less then 10 bucks. Just peel the red sticker off and you have a chrome locking cap that seals . I will probally pick one up today and get you a part # . Called company and they have no clue , so I'm going to take mine in and have them match it . I've seen them on a few 65 plymouths .
