Obviously, the author is quite young, or he would know that radio in the 1960s WAS AM. Although FM existed, few listened. The Four Seasons were A RADIO SENSATION and much more. The AM stations that played The Four Seasons were often simulcast on their coowned FM stations. Not until around 1970, when the FCC decreed that many FM stations could not simulcast, did the “Underground” formats appear on FM. The Four Seasons were too mainstream for the “Underground” FM formats, though by the mid 1970s, most “Underground” stations had evolved to “Album Rock”, playing “Who Loves You” and even “New York Street Song (No Easy Way)”. It’s great that the younger generations are now hearing many of the lesser known hits of The Four Seasons, not just the four mentioned due to Jersey Boys.