Thanks for the best info with detail pictures, I follow step by step and install all 3 new gear and hand turn do see the mileage turn forward and backward, but installed back to my 1988 420SEL go out test drive, it just not turning, I brought this couple weeks and cruise control and clock also not working, I checked the gear on the clock is good and test the power plug do have 12 V there but the clock just like the odometer not turn at all, is there a relay or module control the instrument cluster? Please help!