Description After 30 years, its very common for the factory rubber on the cab mount bushings to sag, crack, and fall apart. This can lead the body line when looking don the side of the truck to not sit right. It can also cause the cab to sit on the transmission and a vibration go through the cab. There are two types of material that can be used for these cab mounts: Rubber and polyurethane. Asking which material is better is like asking someone about their feeling on politics or religion. Everyone has their own favorite. While polyurethane is much more rigid and durable, it is a much harsher material so it tends to transfer the road bumps through the body more. These mounts are the same spec and material as the factory rubber. Comes as a set of four mounts: 4 lowers and 2 front uppers, and 2 rear uppers.