I have mine on the rear next to the vents for the one on the console and on the bow next to the TM for the front 788. I am not sure about mounting the tranducer to the jack plate however. I have my SI puck mounted there and that works fine for that unit, but at high speeds the dual beam on the 788 may need to be lower on the boat so to not loose contact with the water. I think my jack plate, even at the lowest point, is out of the water on a high speed run. I could be wrong.