I just bought an HDS7 Gen 3 and am installing it. I believe it came with the Active Imaging 3-1 transducer, as when I looked up pictures of different transducers mine looks just like it (quite large, extends about an inch past the metal bracket, and is about an inch and 3/4 deep). I am trying to select the correct transducer in the menu, but don't see an Active Imaging unit. I've read that when the Active Imaging came out, it would not work with the HDS Gen 3. My unit has the latest 18.2 version software update, and the transducer plugged right into the structure scan port on the HDS unit. What transducer do I actually have? Which transducer should I select in settings for optimum performance? Will this transducer even work with this unit?