If you decide to not use this Pinpoint, let me know I would be willing to take it off your hands. The Pinpoint system is actually pretty cool. This 7520 has capabilities to upgrade and add GPS. You can also tie other units together and read from the same transducer. I currently am running the TR-320 with a 7420. Dash and rear deck respectfully. I have added the Mapserver for the GPS and it is a great setup. Google the Mapsever for more info on that.
I am currently looking to add one more for the bow. either a 7420, 7520 or another TR-320
Let me know how you like it.
Brian