No Explorist model has an antenna jack. You may use a reradiating GPS antenna Unless you're using it in an enclosed area like the hull of a boat, you're unlikely to find this necessary.

Magellan sells windshield plunger mounts. Some people report success with vent clips or cell phone holders in their car such as the Radio Shack 17-548.

Gilsson makes the Gilsson MEN GPS case.

Cartom Explorist cases