Sonnax has introduced Second Gear Servo Kit (part no. 77701-02K), which is a direct replacement part for GM 4L70-E transmissions.
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Sonnax says this kit can improve shift feel without risk of harsh 1-2 shifts in GM 4L60-E and 4L65-E transmissions. This kit is also compatible with Sonnax Fourth Gear super hold dual servo kit 77767K.