man i like those ol Macks! 
mine is an 86 ford 8000, with a hiway CAT tractor engine. It stinks, is loud, is slow as a sloth but will pull a cruise ship out of the water....lol
worst load i have had was 12 yards (yes only 12 yards) of wet CLAY.......... it made the nose of the truck rise up 9 feet off the ground, and basically sat the truck on its arse end wheels and the rails.....made me sweat, a bit. ok a lot.
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