The answer is likely along the piping on the top edge of the cap band underneath the overhang in the rear of the hat. A 99 and 44/100 % chance it will be light blue.
Mike, if you want to send to me for inspection, Art and I can take a look at it, and get photos comparing it with our transports in sun, shade & w/ a flash.
Gents, it has to be Transport, simply b/c it is a pre-patent Erel, and Propaganda Light Gray was not introduced until January 1943 (prior to then, they utilized Signals Lemon-Yellow).
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