I knew I was going to be asked that! I might have a GM of Canada photo somewhere of a similar truck. However if anyone can guesstimate the wheelbase from the photo here is the definitive list of all in theory available Canadian Chevrolet and GMC trucks.
CANADIAN CHEVROLET AND GMC SCHEDULE
The GMC pictured is a 1941 Model...note similarity to the 1941 Chevrolet though not all US GMCs had that grille...some had a '40 style to 1942. I am sure that the desert truck is a '41 Model.
Note ML and Chevrolet shared the same grille more-or-less but ML had 'MAPLE LEAF [LEAF MOTIF] TRUCK' instead of 'GENERAL MOTORS TRUCK' and a Maple Leaf hood badge. In reality they were clones of GMCs although equipped with Chevrolet engines or the 224 Chevy-based Canadian Pontiac unit with one notable exception: in 1940 Model Year only an imported 248.4 cu in GMC six was used in ML and GMC. Then in August 1940 for about a year Windsor Plant produced an indigenous 248 although not used in any ML trucks. As you know there was a 1939 discussion about using the 248 in military Chevrolets vice the 216.