I broke the mounting bracket on my ancient Lowrance Globalmap 1600. I want to replace it with something newer and faster. It has an external GPS antenna input and a separate proprietary NMEA connector. I can't seem to find a direct replacement GPS map unit. Any ideas what will plug in? I don't need much on the lake. Mostly I set waypoints for the slip and a few spots on the lake to avoid. By the time we might relocate to a larger lake the next unit will probably be due for replacement also.