ChevyJr, your left yellow circle is the area where these parts join. your left yellow circle is of the passenger side. My first photo shows this same area on the driver's side. the long inner brace fits OVER the outer brace. the spot welds you see are most likely to hold the inner portion of the cab support which keeps the cab bolt from crushing the floor and brace if tightened too much (see your original picture). these spotwelds MAY also help hold the outer brace to the inner one, I don't know cause I didn't go that far. you should be able to see all this on yours cause you have the floor out of the way in that place. the inner brace is also spotwelded to the floor pan, hope you bought more than one spot weld cutter
Edit: it looks like, in your photo, that the "crush" piece is spotted to the rear of the cross brace, which suggests that the spot welds in my picture join the inner and outer braces