The u-joints on the driveline of a 2003 Chevrolet Silverado are flexible joints that connect the driveline to both the transmission and the axle. These joints allow the rear axle to move up and down with the suspension while the driveline is simultaneously able to rotate. These u-joints wear down over time, and eventually they start to knock and make noise. and can fail. When this happens, then the driveline won't function properly and could break entirely from the axle. Before this occurs, you should replace the u-joints when you start noticing noise or wear.
Lift the rear axle of the truck with the jack, and put jack stands underneath the axle. Place wheel blocks around the front tires. Put the drain pan beneath the transmission.
Unbolt the driveline from the axle using an open-end wrench. Pull the driveline from the axle using the pry bar, then pull the driveline out of the transmission with both hands.
Remove the clip on the u-joint at the end of the driveline using the pliers. Set a socket on the end of the u-joint that's the same outer diameter as the inner diameter on the u-joint. Strike the socket with the hammer until you can grab one of the u-joint caps with the pliers. Pull the cap off, then remove the u-joint from the driveline.
Insert the replacement u-joint in the driveline. Install the caps on the u-joint with the hammer and socket.
Install the driveline into the rear of the transmission, then install the other end into the axle housing using an open-end wrench. Lower the Silverado off the jack stands using the jack.
