Working Takeout.
This is an Airmar / Raymarine transom mount transducer, model p65, that fits the DSM300 and other Raymarine units with that plug.
31-417-3-11 Rev A
P65
E66007
50/200kHz
NOTE:
The transducer mount clip (the clip the holds the ducer in the down position) got broken off. The ducer is held in the down position by 2 screws which is sufficient nevertheless it's not original. :-)