identify the odd bracket- C60L Aust

[Darrin Wright]

On the weekend I had a look at some vehicles in a collection and came across this bracket that as me puzzled, I have seen it in a couple of trucks over the last 15 years.
The bracket is located next to the fire extinguisher bracket inside a Chev C60L with drop side tray. Truck was made in April 1945. No bren mount fitted to the cab. Cab had canvas door frames and a drivers sun visor. Melbourne assembled truck.

any idea....anyone....

Thanks