I suspect Bill O’Reilly’s  “Radio Factor” affiliates already knew this but Fox News veteran John Gibson has been tapped as the one to fill the void left by O’Reilly’s departure from radio early next year. The revamped “Gibson On Fox” gets the O’Reilly 12p-3p time slot on Fox News Radio starting January 19th.  Gibson’s retooled show will feature his contrarian take on the headlines as well as guest news makers from the business and political world. O’Reilly had announced last week that he was stepping down from his Westwood One syndicated daily radio show because of his television commitments.