The front driveshaft on a Ford Ranger connects the transfer case to the front axle. When your Ford Ranger is shifted into four-wheel drive, the transfer case splits the power generated by the engine between the front and rear driveshafts, which in turn sends power to the four wheels. If you notice excessive vibrations coming from underneath the vehicle while four-wheel drive is engaged, you may need to replace the front driveshaft.
Raise the front of the vehicle using an automotive jack, and support it with jack stands placed under the front axle.
Pull back on the rubber boot between the front driveshaft and the transfer case, with your hand.
Unscrew the nuts, bolts and straps that connect the front driveshaft to the front axle yoke, using a wrench and socket.
Slide the driveshaft underneath the front axle while pulling it towards the front of the vehicle. This will separate the splined shaft from the transfer case.
Coat the splined shaft with multipurpose lubricant C1AZ-19490-B or equivalent.
Slide the splined shaft into the transfer case.
Set the universal joint into the front axle yoke.
Reinstall the nuts, bolts and straps that secure the universal joint to the front axle flange. Torque the fasteners to between 10 and 15 foot-pounds.
Slide the rubber boot onto the transfer case.
Lower the front of the vehicle.
If the driveshaft will be removed for an extended length of time, then plug the hole in the transfer case to prevent moisture from contaminating it.
Always follow the instructions listed in the owner's manual when lifting and lowering a vehicle. Failure to do so can cause injury or death.