The GM 4L60, 4L60-E, 4L65-E and 4L70-E input drum assembly is known to crack and strip out splines where the input shaft is pressed into it (where the overrun piston rides). Sonnax offers a hardened steel sleeve that reinforces the input drum to prevent this failure. Sonnax input housing overrun sleeve kit 77733-51KA includes a custom manufactured overrun piston designed for use only with a stamped steel forward piston, eliminating the need to use aluminum forward pistons. For additional torque capacity, this kit can be used in conjunction with input housing forward sleeve kit 77733-52K.

• High-strength, chromoly steel sleeve increases input housing torque capacity by protecting the shaft and overrun piston areas
• Custom overrun piston works with steel forward piston
• Universal design fits both early- and late-style units