There is an obvious difference in the length. The 41-46 cabs are about 2 inches longer than the 39-40 cabs. That makes the running boards about 2 inches longer as well. It might be possible, it might not... probably depends a lot on skill level.
i did a little homework after reading your message and it appears that in '41 chevrolet repositioned the seat and added a bit of leg room.
ive got a '40 truck front clip at a different location and like the simplicity of it. if the swap worked w/o much fuss id have done it... when i get it to my garage ill do a test fit to see where its off at and at some point post my findings in this thread.
not looking to hack up anything or spend a whole lot of time making it work. im sure there is someone with a '40 that needs front sheet metal.
thanks for the replies.