Kind of off topic but I have a mount and cable for a Garmin GPS/GPSMAP 76 that someone can have. You can pick up the standard GPS 76 w/o mapping for around $50 buck on ebay and here's a free mount for you. If someone wants it let me know.
https://buy.garmin.com/shop/shop.do?pID=799
and the cable will run into a VHF etc.
-Svence