I believe there are some subtle differences between 39 and 40 chevy grills, but I am 90% certain it will work. You might have to use the 1939 top piece too. I am only speculating.
My advise to you is to forget about the grill and sell the truck to me. Obviously nobody will want a 1940 suburban with a 39 grill, so you will be a head of the game if you just give me the truck.
All kidding aside... Welcome to the Stovebolt page, and good luck with your truck.
