This procedure is specific to the DTR sensors used on 4R7DE and 4R75E transmissions and does not apply to the TR sensor on 6R80 transmissions, which is an integral component of the valve body and cannot be serviced at home. The DTR sensor is located on the left side of the transmission. If replacing the DTR sensor or removing it to replace the transmission, a special alignment tool (307-351) is required. Begin by putting the shift lever in Neutral and disconnecting the negative battery terminal. Raise the vehicle securely on jackstands. For some 4WD models, it may be necessary to remove or disconnect the front driveshaft. Disconnect the shift control cable from the manual control lever and the electrical connector from the DTR sensor. Remove the manual control lever nut and the lever itself. If reinstalling the same DTR sensor, mark its relationship to the transmission case; if replacing it, the special tool is necessary for proper alignment. Remove the DTR sensor mounting bolts and the sensor, ensuring the manual selector shaft remains in the Neutral position. If the selector shaft has been moved, return it to Neutral by rotating it through the gears and then counterclockwise three detent positions. Before installing the DTR sensor, align the Neutral marks on both parts of the sensor. Install the DTR sensor on the manual selector shaft and loosely install the mounting bolts. For the old sensor, align the previously made marks while tightening the bolts securely; for a new sensor, use the alignment tool before tightening the bolts. The remainder of the installation follows the reverse order of removal.