2001-2010 Billet Output Shaft Allison 1000 And 2000 Series (128021000)Description High horsepower levels and heavy duty use stress transmission parts past what they were originally designed to handle. The Allisons output shaft is a common failure point so PPE offers this Billet Output Shaft for high performance transmissions. The PPE shaft has been specially designed to withstand the higher horsepower (over 800 RWHP) and torque levels that come with high performance engines or the added stress from towing or racing.