Darren,
I'm not sure if its the same for the Aussie engine color, but as I understand the original color on the the Canadian Carrier was a dk green color, the same color as the Ford civilian production colors. When the engine was replaced or overhauled by RCEME it was re-painted Grey. Same goes for the transmission. I understand this was a post war thing.
What is that rack/box thingie for on top of the engine deck?
Here is a photo of mine...
Original photos of CDN engines...
