I've seen a few WW2 period pics where different parts of the vehicle is painted in different colours.
Look at this Ford being assembled below. The Frame and front bumper are painted a different colour to the Cab and wheels, and the frame may or may not be the same colour as the interior as the Cab, which is in turn a different colour to the underside of the engine cowling. What colour would you describe this truck as, yellow or green?
Source:
Ford Canada Factory....