Friend of mine runs a HB900 Series with SI and DI and 2D at the bow. He recently picked up a new take off fortrex with a built in transducer. Am I correct that this built in sonar on the fortrex is only good for 2D mode and that it will not work for Si and Di. Hes coming from a motor guide so he has the appropriate Di,Si,2D transducer that will clamp on. Just planning ahead for the install.