GN047+SPC-35: i.Trek Removable Swivel Air Vent Mount for Garmin Nuvi and Garmin StreetPilot w/ 3.5" Screen Protector for Personal Navigation Devices (Bulk)
Purchased the mount and found that it was much better and more secure than other suction cup mounts that Garmin offers.  Only drawback that I found was that with the GPS installed on the mount, it can become dislodged from the air vent when traveling over a rough road or hitting substantial bumps in the road.  However, that said, the Nuvi swivel mount is the best option that I have found and I am very happy with it.  Dan