Truck owners and mechanics, this Poly Pacific exhaust bushing set is exactly what you need for maintaining your Peterbilt exhaust system. The 4-piece set includes high-quality polyurethane bushings that are far superior to standard rubber bushings - they're more durable, resistant to heat and chemicals, and provide better vibration damping. The part number 21352 ensures you're getting the correct fit for your Peterbilt stack system. Polyurethane holds up much better against the extreme temperatures and constant vibrations that exhaust systems endure, meaning you won't be replacing these nearly as often as standard rubber bushings. The set includes everything you need for a complete replacement job, saving you from having to piece together individual components. Installation is straightforward for anyone familiar with exhaust system work - just remove the old, worn bushings and install these new ones. The improved material quality means less downtime and more reliable performance from your truck's exhaust system. Perfect for routine maintenance or repairs when your current bushings have deteriorated from heat exposure and road conditions. This is one of those upgrades that seems small but makes a significant difference in the longevity and performance of your exhaust system. Keep your Peterbilt running smoothly with these quality replacement bushings.