I can rekey a 1966 and up door cylinder in about 10 minutes, while a 1962-65 cylinder will take me about 40 minutes. I have done the early locks for a few Moparts members. Also a lot of locksmiths will not even have blanks for the early locks as the grooves on the sides of the lock were different 1959-65. A well worn down early lock will sometimes take the later key blank.