In one of the weirdest promotions of all time, Diamond REO shipped a brand new prototype dump truck to Africa in 1967 and pre-ran the entire route of the East African Safari Rally. This was an insane feat of endurance and strength as the rally was basically a 3,000 mile trip on dirt roads with dangerous bridges, narrow roads, mountain terrain, and outright peril. Three guys drove the truck the whole way and they managed to finish the route with an claimed average speed of about fifty miles per hour. 
Is that true? Who knows, but there's loads of evidence that these are some of the hardest core dump truck drivers who ever lived. A Detroit Diesel engine and a 13-speed Road Ranger transmission powered the rig over hill and dale. Incredibly a documentary film was made about the whole adventure. 
Here's the story of the weirdest dump truck drive of all time.