Thanks. The first link is a great article, despite the super-simple graphics and weird math notation. I especially liked the description of shear and normal forces. Only one typo (3-box body in the 1930s not 1960s).
Here's a good takeaway. Maybe I should stop worrying about my drip-rail vortexes.
I purposely didn't read the second link so I could prophesize that it's a Canadian delivery truck. Am I right?