In '52, they changed the handle from the turn style to a pushbutton type, the same handle was used to the '66s. With that handle, the outside lock is part of the handle mechanism, specifically, in the button, than mounted in the door itself. According to the Standard Catalog of Chevy Trucks, the left hand door lock was available, RPO 395.
My '55 did not have the external drivers side lock, either, but I added one by swapping out the button.
