GM 4L60 (700-R4) and 4L60E series reaction shafts often suffer from spline twist and wear in high-torque applications due to the soft, weak steel of OE and most aftermarket shafts. This new Sonnax heavy duty reaction shaft (#74602-01K) is made from high-strength chromoly steel alloy to eliminate these problems. It's also a universal fit for all carrier styles thanks to the included bearing and shim, making it an easy, reliable way to build extra durability into any big power 4L60E transmission.