Car DC Power Adapter Charger Cable for Garmin Streetpilot C340 C330 C320 C310 GPS
This adapter came very quickly, and works great with my Garmin C330 Streetpilot.  The only thing is that the cord is only so long, my accessory plug is near the floor of my van and to stretch the cord so I can put the GPS on the windshield is a very tight stretch, it does just make it, but worry that it'll eventually pull the wires out.