Machine description: Paccar PX-8 6 Cylinder 8.3 L Diesel 300 hp Engine, Positive Air Shutoff, Engine Brake, Allison 3500 Automatic Transmission, Differential Lock, Dana Drive Axles, 5.57:1 Axle Ratio, Air Ride Cab, Alumin... more info about the 2012 Peterbilt 337.