I have a splitter a buddy gave me. And I want to glass in a 2 D transducer in hull for running and have my side scan transducer for scanning. My question is do I have to manual switch from one transducer to the other or will unit switch automatically when I go from 2D to side or down scan? And which 2D puck transducer do I need to order for a Gen 2 helix unit? Thanks!!