It all depends on the speeds you're trying to do that work, now doesn't it?
My 2007 LBZ Duramax, for instance, makes 650 lb-ft at 1,600 rpm. I like to run 75 mph, and have 33" tires (32.8" actually). In 6th gear (0.62) I'm turning 1750 rpm at 75 mph with the stock 3.73 gears. With 35" tires...