THE DRIVE LINE: The drive line itself requires virtually no maintenance but occasionally the U-joint which links the live rear axle to the stationary transmission will need to be replaced. To check for wear, firmly grasp the drive line near the Universal joint, move it up and down feeling for play. If any play is present, you'll need to replace the U-joint. If the U-joint becomes badly worn, you can hear it as you drive and as you shift the car from forward to reverse. There are two sorts of problems that can occur in your differential. One is a leaky seal commonly called a pinion seal that will allow the fluid in the differential to escape. If you notice oil on the floor or oil in the vicinity of the differential, you'll need to take it to a professional mechanic for repair. If you begin to hear a howl in your differential or in the vicinity of the rear of your car, it generally means that your differential is worn out and will require complete replacement.
