Our ultra-durable input shafts are constructed from 300M alloy, which is a modified, heat-treated 4340 steel that is proven to be stronger than stock or other aftermarket input shaft materials and resists breaking and twisting in order to handle 1000+ horsepower applications. Precision-ground bushing rides ensure a smooth surface to eliminate premature bushing failure while the rolled splines further increase strength by replacing the unnecessary hobbed area that typically occurs when shafts are cut with a gear hob. Instead, the rolling process actually compacts the splines, causing the material in this area to be denser and therefore, stronger. Their higher yield strength results in less shaft twisting than standard OEM material, additionally reducing the stress that shaft twisting often introduces. These 300M Input Shafts for GM 4L80E Transmissions will provide optimum stress distribution along the entire length of shaft in high performance transmissions. However, they also fit as stock replacements and require no modifications for installation.