I don’t know about the Mark 5x pro but the 386ci and 386ci DI models both radiate the sonar out of the bottom of the transducer, so there should not be a problem with mounting the transducer next to the other transducer. However, operating them both at the same time may be a problem as I am guessing that the Mark 5x pro uses the same 200kHz frequency as the two 386 units. This will give the possibility of sonar-to-sonar interference.