TransGo # SK 4L60E Shift improvement / correction kit Corrects/Prevents/Reduces: No lock-up or 4th and code 1870. Cutloose & bang from reverse to drive; forward and low/reverse clutch burnup. 1-2 bump; double bump; slide-bump; delayed reverse engagement hot. Includes new design PWM boost valve. Also corrects worn valve body, rough shifts and blinking light. No special tools needed.