Yep Bill, a '39 1/2-ton anything would be a JC. The J stands for 1939 and the C is a 1/2-ton. Includes pickups, panels, Subs, Canopy Expresses and anything else rated at a 1/2-ton. The rear fenders would be the same from '39-'46. Make sure the fender is for a 1/2 or 3/4 ton for sure and not the larger 1 or 1-1/2 ton panel with 20" tires.
By the way, pickup fenders bolt flat to the box sides and panel fenders bolt up into the fender opening on the body like a car fender does. Hard to confuse them if you remember that.
