Storm Bringer wrote in to add " http://auto.howstuffworks.com/1939-1940-studebaker-champion6.htm which shows a photo, and says:
The most involved conversion for the 1940 Champion coupe was the "coupe delivery," or "pick-up coupe." This involved a cute cargo box measuring 31 inches wide and 18 inches high that could be slid into the trunk cavity as needed (the trunklid was furnished loose). There was even a tailgate with stamped-in "Studebaker" lettering. The box sold for just $25 in black, $26.50 if painted another color.
Also Hudson at the same time offered a pull out pick up box "