There should be a assembly date code on the Holden tag .
As an example: On my 1940 Chev. A0 = Jan. 1940.
The letter refers to the month and the number is the year. C1 = March 1941.
They (GM-H) sometimes used DLX = Dulux as the colour code prefix.
Looks like your colour is BRCS or BRGS ?
Some of the Holden colours for 1940:
Wirraway Blue
Coolangatta Cream
Oodnadatta Beige
Bundaberg Beige
This has more info:
https://www.hcvc.com.au/forum/OldTru...wledge?start=0
My neighbour down the road is from Coonabarabran.