From 1939-1945 Corbitt designed and built over 3,200 50SD6 six-ton, 6×6 prime movers for the U.S. Army. These trucks were equipped with either the 779 or the 855 cubic-inch Hercules 6-cylinder gasoline engine. They were used in every theater of operation during World War II. Corbitt lacked production capacity for all the trucks needed, so White, Brockway, Ward LaFrance, and FWD all built the same or very similar trucks. Altogether, over 10,000 of these trucks were built by the five manufacturers.

Looks like a Corbitt.

" … but should we grab our tire irons and see if he’s a German spy?"

And you'll see them. The aliens, I mean. In ships shaped like saucers.

There are only about 17 miles of US 40 in Delaware, between Maryland and New Jersey. Though it was a major highway, in 1943 you got into New Jersey by ferry across the Delaware River, replaced in 1951 by the Delaware Memorial Bridge. US 40 was originally the historic National Road (1811), but none of that was in Delaware because it headed west from Cumberland, MD.

The stretch of US 40 that John Vachon photographed is still there; you may find yourself stop-and-going on it if you decide to take a break after the southbound New Jersey Turnpike and the Delaware Memorial Bridge.

[Below, Vachon's photo (an inadvertent double exposure) of "trucks on the Pennsville Ferry between New Jersey and Delaware." - Dave]