I have a 02 that already had the factory CB antenna installed. So changing to Sierra's dual antenna's was obvious. The wife has a 04 ordered to replace a Valkyrie Interstate. She wants to see dual antenna's. Do you have to purcahse a CB antenna to then only use the mount to be able to use the dual antenna's from Sierra. I already know how the Sierra antenna's work. AM/FM becomes AM/FM/CB with a splitter and the factory antenna becomes a dummy. The question is about the mount only. TIA!