Non veni pacem mittere, sed gladium.
Not "timbers". That's the fuel tank. My pop had a "split shift" Rio set up the same way when I was a kid. --Ray
Look on the left and right side of the cab, just behind the stacks. Looks like two thick boards attached to the back of the cab or behind it. No matter, logs like that would sweep through anything in a wreck, tearing that truck in half. Bad, bad, bad.
Is that an auxiliary gas tank atop the cab (or an air tank)?
Poor people have poor ways.
Back in the 60's my Grandfather worked for Weyerhaeuser in Oregon. They had their own haul road from the woods to the mill in town because they ran log trucks with 10' wide bunks which were not legal on the public roads.