Front fenders YES, to my knowledge the perimeter of the 39 fenders and the 1940 car fenders are the same.
Grill assembly NO, the hood is different (39 hood the same shape as 1940 standard). The hood would need to be replaced also. In addition early 1939 had a different latch than later 1939 (and 1940 standard) so care would need to be taken to make sure there is a match.