Doesn’t turn off when I turn the key to OFF position

So I just installed a new 130 amp one wire alternator and went to take the fury (1966) for a drive. When i pulled up to the gas station I turned the key to the left and the car remained running. I ended up inserting the key back in and leaving the key in the off position and after a couple minutes it shut off. Is this something simple like replacing the ignition tumbler and ignition swtch?
Author: slappo