You'll need a serial number in the majority of cases unless you know exactly what you need. The serial number is equivalent to a vin number, but is only recognized by Maxon (i.e. you won't be able to check the history of your gate from any external system). We cannot trace gates using the vehicle's serial number which the gate is attached.
What information does Maxon's identification label contain?
Every Maxon gate out of the factory comes with a steel identification plate which includes the serial number, model, and date of manufacturing. This is helpful in order to confirm what parts you need and the history of your gate. If you have this information you're golden.
Where is the plate located?
On tuck under style liftgates, the majority of identification plates will be located on the passenger side of the gate, on the main frame or on the platform.
Column and rail lifts will usually have the identification plate on the inside of one of the rail columns.
On the GPC and cantilever models it will most likely be on the driver's side of the gate: