Driving diesel in very HOT temps - 103+ and long grades

Just drove the southwest late July with same heating issues. 350 Cat. Spray off your radiator before you leave. Mine worked best at about 2,000 rpm, keep down shifting. I had to hit 1st gear a few times, about 20 mph, turn your flashers on and drive slow. To cool down if needed pull over and rev the engine and your temp will come down then.