On the Original Box:
The Unit ID is a 10 digit number found internally when viewing the system information on the device.
Under the Battery Inside the Battery Compartment:
See the video below for instructions to access the battery compartment.
Every Garmin automotive device will have a unique serial number and Unit ID number to identify it. The serial number is a combination of 8 to 9 letters or numbers, without spaces or dashes, externally printed on the device.
The Unit ID is a 10 digit number found internally when viewing the system information on the device.
See the video below for instructions to access the battery compartment.