I have what I have been told is a 1963 convertible impala SS 409. My vin is 31867J266335. However I have just recently been told, if the # after the first 3 is 14 it is an ss and if is 18 it signifies that it is a v8. I have also been told that there is no such thing as a 314 opening sequence for a 63 , and the 14 designation for an ss was for 64. Does anybody know definitively ? thanks for the help