My answer is based on my own truck, which is still in its original paint, several other 41-46 trucks also with original paint, several factory photos, and dozens of old photos.
Here is a nice collection of vintage photos:
Click. See if you can find a truck which does not agree with my findings.
You will notice that when "restored" trucks do not have that area between the upper and lower grilles painted, they generally also lack the cab pin stripe, another nice original detail.