These bushings offer great vibration isolation and will not crack or breakdown like the OEM foam or rubber bushings. Also comes with corrosion-resistant coated steel cups. Stock body mounts deteriorate over time and cost a fortune. Urethane mounts are hard and squeak. S&B's Silicone Body Mounts have a smooth stock ride and last the life of your truck. The cap bushings have a distinct boss feature on it that matches the slot on the mounting tabs. They are designed to key into the frame tab and give it an OEM fit.