The new 12.8-liter DD13, aimed at vocational and weight-sensitive trucks, weighs 2,200 pounds and makes as much as 450 horsepower and 1,650 lbs.-ft. The builder says the new engine is up to 5 percent more fuel efficient than the one it directly replaces, the MBE 4000. DD13 can be fitted with a rear- or front-engine PTO, and claims easy maintenance and oil-change intervals as long as 50,000 miles.