How To Recode A Door Lock

Do the pins just go in random order or are there seperate pins to a lock? Ie. can you make one into another just by changing the pin positions? We bought a beater 76 Coupe DeVille with one key and the ignition key didnt fit the doors! Found out the first night we took it out to a bar. F'n guy must have changed the ignition cause we were locked out. Had to bust the rear side window to get back home to base before we were UA. Drove that ***** from So. Cal to Chicago that weekend with a broken window. Didnt look good.