TCI® Hardened Input Shafts are constructed from hardened, aircraft quality Vaccu Melt 300 billet steel or Vasco 300 high strength steel. They feature increased lubrication flow and strength with a resized diameter that provides optimum stress distribution along the entire length of shaft and along the extended high gear splines to the oil ring. See the chart below to compare the TCI® Input Shaft materials compared to the stock and other aftermarket brands.