Moving parts need lubrication. It's one of the few constants of the world. Your Chevrolet axle assembly is no exception. It transfers rotational force between the wheels and the transmission. The transfer should be seamless -- carefully greased and packed CV- (continuous velocity) and U-joints keep a great deal of abrasive dirt and grime from penetrating the joints and avoiding wear. The rubber gasket forming a seal around the CV-joint is called a boot, and must be tough to stand up to the elements encountered by Chevrolet cars and trucks. Many people find out they've got a cracked or torn boot while performing routine maintenance. If the problem is not taken care of in a timely fashion, a grinding noise may develop, often getting louder as the wheel is turned. The longer that noise continues, the worse the damage will be. Very often CV- and U-joints are often too damaged to use once you've heard or felt grinding. While some people try to save a few dollars by reusing old CV or U-joints when replacing the boot alone, this practice rarely gives satisfactory results even if you have the special tools to crack open the boot. Often, by not replacing the whole Chevrolet axle assembly, one spends far more in labor than on the part to install a damaged joint into a boot that isn't tight. Why do the job more than once? If you want a reliable repair, car-stuff.com offers OEM-quality Chevrolet axle assemblies that are very reasonably priced and will only need to be replaced once.