Sonnax Smart Shell Reaction Shell Heavy Duty Reaction... Enclosed Thrust Bearing... Custom Roller Clutch Race Stripped or cracked shells in GM 4L60, 4L60-E, 4L65-E and 4L70-E units are a common problem, but strengthening the shell alone does nothing to address the equally common problem of a failed rear planet captured bearing. The Sonnax SmartShell 77749-02K is a heavy duty reaction shell kit designed to prevent damage to the rear planetary assembly as well as provide a reinforced shell.Protecting the Planetary BearingIn the OE sun gear shell, the thrust load passes from...