42' panel truck,
You haven't given us enough to go on to really give you the best answers possible. According to this resource document
1942 Chevrolet Truck Data, there were at least 4 different sized "panel trucks" offered in '42.
Can you let us know which one you have??? A rough guess based on your current rear axle ratio being "4.56" would seem to indicate you have a 3/4 Ton on first look (but there are actually 3 different 3/4 tons including the standard 3/4, 3/4 Heavy Duty Equipment and a 3/4 "Special").
Please come back and provide more info on what truck you actually have so folks can better try and answer your question.
Dan
