As long I can remember 1964 has always been the cut off date for Hot Rods and Customs when it comes to shows and events. Here lately I've even seen 1963 as a cut off date. My question is "Why 1964?" or 1963? What are the big things that differentiate a car made in '64 from say one made in '65 - '70. Are '64 and up considered Muscle Cars (obviously not all of them)? Anyone care to shed a little light on this?