Allison 1000 4×4 Output Shaft 2001-2010. This shaft is made in-house at TCS for heavy duty towing & competition applications. All TCS shafts are made from Select Grades of Super Strength steel alloys and are approx. 50% stronger than the O.E.M. versions. This 4X4 output shaft is: Made from 300M Billet steel. Ideal for heavy duty service applications. Precision ground for high dimensional accuracy. Ideal for those who challenge their vehicles at work or at play.