4L65E Hardened Input Shaft for LS1 Type Transmissions. We take the new stock hardened 4L65E shaft then have a heat treating process performed to improve rigidity and strength. These are much more rigid than the factory 4L65E shafts. We rate these double hardened factory shafts up to 580 torque! Made from new OEM 4L60E input shafts. New 4L65E shafts are stronger than new 4L60E shafts.