CARGUY, THE DIFFERENCE IS IN THE VENT GLASS. 39 HAS NONE. SEDAN AND COUPE ARE NOT THE SAME, SEDAN IS ABOUT 8" LONGER. YOU CAN SWAP BETWEEN THE YEARS, AND MANY GUYS HAVE ELIMINATED THE VENT WINDOW ON 40'S. HINGES AND LATCHES ARE THE SAME. THERE IS A DIFFERENCE IN STAINLESS TRIM, HOWEVER I AM PRETTY SURE HOLES ARE THE SAME, I COULD CHECK THIS IF YOU NEED TO KNOW.GOOD LUCK.