The GU uses a Wheel Bearing Lock Nut and Lock Washer (it has lots holes around it for a couple of screws) in the GQ they used a Lock Washer which was between the two Adjusting Nuts and was bent over to stop the Nuts from becoming lose in Manual Hubs. They also used the Lock Nut and Lock Washer in GQ's if they where fitted with Auto Hubs so your right you don't need it.
It is a common mod to change the bent washer with the Lock Nut/Washer if you have manual Hubs.
It is a common mod to change the bent washer with the Lock Nut/Washer if you have manual Hubs.