There was a good reason to modify this business coupe trunk into a truck bed. More gas rations during WW2 for trucks.

Here are 3 photos of the same thing, as I found different small details of the pickup bed area in each photo that I think show how easy it was to remove the trunk lid and put in a bed

I learned this from Bob Engels http://www.bengelsoff-road.com/homepage/homepage.html who will be working some magic on a Lincoln Zephyr that had a similar conversion in the early 40's (for the added gas rations)