F550 LARIAT, Medium Duty Trucks - Versatile Hauler Trucks, Powerstroke 7.3, Automatic, This hard to find F550 Lariat is in excellent condition with a 7.3 Powerstroke engine. Leather seats, power lumbar drivers seat, power windows and door locks, fold down back seat, Horse Power, Air Ride Suspension, Wheels, Wheel Base, 225/75R19.5, Axle, Ratio,