Street tube size but I don't know what they fit. Only part number I can find on them is 12. Couldn't be hedman, hooker, doug thorley, or casler, I know they fit SBC engines. Would have to be something around before the mid 80's. If I had to guess I would say full or mid size cars but I really don't know, could likely be pickups too. Nice shape though. Priced cheap because I can't pinpoint application.