When did production of the #13 cab begin?

[Ryan]

I have just purchased a shorty Ford F15 4x2 Blitz, number 13 cab.
It was last registered for road use in 2007 and on the sticker it says it is a 1941 Ford. I thought #13 cabs were 1942 or later. So my question is when did Ford begin production of the #13 cab. Did Australian production start at the same time as Canadian?
I don't have a chassis number yet and the data plate is missing.