Model 1541 was basically the same as the 1542 and 1543, but and you raise a fair point, as per US Chevrolets twin wheels were available as 'Heavy Duty Equipment". The near-identical 1543
CC60L was produced in three known military versions:
1543X1 with DUAL REAR CIVILIAN WHEELS
1543X2 WITH SINGLE REAR MILITARY WHEELS
1543X3 WITH DUAL REAR CIVILIAN STYLE WHEELS
with "X1"being export to "any Point Except Fully Built Up"
"X2" for "United Kingdom Fullly Built Up"
and "X3" for "India CKD"
Now thanks to you I remembered that I could prove that there were indeed wartime GM of Canada exports to the NEI: "X6" was the destination code for "Batavia, Netherlands East Indies CKD", with by example "South Africa" was "X9", although GM South African used their own code "XG" in front of the Model Number, and "New Zealand" was "X5" although they used "XH". GM (Australia) may have been allocated five "X" codes in the Twenties [posibly "XJ" to "XN"] but never used them and Holden-assembled GM of Canada vehilces never had an "X" code...they used the Branch Aseembly Plant codes instead.
So, if you ever found a NEI-assembled GM of Canada vehicle it may have a VIN or chassis number of say "11541X6012345" where "1" was "1941 Model Year", and "012345" was the sequential number BUT only if it was fully-assembled. CKD vehicles would be I suggest "XQ1541-1234" where "XQ2 was "Batavia Plant", and "1234" the sequential production number.
As regards US exports the jury is out on whether the chassis had US-style codes such as "2MS01012345" where "2" = "Tarrytown", "1" was "Flint" which also produced military trucks pre-Pearl Harbor, then the Model Code, then the production month beginning with "01" for "January", then a sequential number. The alternative was CKD from Bloomfield, New Jersey Boxing Plant, in which case the chassis number might be "XQMS-1234" or variations on that with "XQ" indicating local assembly.