My February 41, May 42 and Sep 42 parts truck all have clutch head for nearly everything in the cab less the floor and toe board. Even the door hinge screws are clutch head.
If the truck was messed with in the past, the clutch head screws are often discarded and more common slotted or philips were used.
If you are looking for slotted screws, they are 8-32.
