Differential Assembly: Application and ID

Driveline System

The driveline is composed of the following:

- Front driveshaft
- CV joints
- Front drive axle
- Front axle halfshafts
- Rear driveshaft
- U-joints and flanges
- Flex couplers
- Center support bearings
- Rear drive axle
- Rear axle halfshafts

The source of the drivetrain's power is generated by the engine and delivered to the transmission. The driveline transfers the engine torque through the driveshaft to the axle.

- On Rear Wheel Drive (RWD) vehicles, power is transmitted through the transmission to the driveshaft and then to the rear axle.
- On Four-Wheel Drive (4WD) vehicles, power is transmitted through the transmission and the transfer case. The transfer case directs the power to the rear driveshaft and then to the rear axle. When engaged, it also transmits power through the front driveshaft to the front axle.

The rear driveshaft is connected to the output shaft of the transmission or transfer case and to the rear axle. The front driveshaft is connected to the transfer case and to the front axle. For Expedition, slip yokes are used to allow for any changes to the length of the driveshaft. Navigator RWD vehicles use a fixed flange at the transmission with a flex coupling. Changes in length are self adjusted up in the driveshaft slip mechanism. The engine torque enters the axle through the drive pinion, which rotates the ring gear. The ring gear is mounted to the differential case, which contains the gears that transmit power to the rear axle halfshafts or front halfshafts. These halfshafts rotate the drive wheels.


Axle Identification

The axle ratio may be verified by checking the printed label on the axle housing. If worn or not visible, the Vehicle Identification Number (VIN) can be typed in the service parts ordering system or the Vehicle Certification (VC) label may be used to correctly identify the axle and ratio. Refer to the chart below.





NOTE: 3L73 refers to 3.73 gear ratio with limited slip.

The VC label is located in the driver door jamb. The first 2 digits of the axle code indicate the rear axle and the third digit refers to the front axle, if equipped. For information on the VC label, refer to Identification Codes Application and ID.