I'm still kinda new to the new technology of fish finders but I did ALOT of research on lowrance units before I bought my units. I have two hds5 gen2's at the console and an hd7 gen3 at the bow. As long as my thinking is correct all you have to do is run power and use an Ethernet cable between the two units and you should be able to see everything on the new unit you can see on the exsisting unit. I believe what you need to do on the new unit is select the sonar source as the existing hds unit. No cable split needed. I know on my two hds5 units only one of them is connected to a transducer and I can view 2d, downscan, and side scan on both units I just don't remember exactly the settings to do it. If you need more help pm me and I will look at all my settings and help any way I can.