The Peterbilt 579 Cab/Sleeper/Extender Kit is a practical and efficient solution for underbody exhaust systems. Designed for 44 inch sleeper models with 123 inch BBC underbody exhaust, this kit is available in stainless steel and measures 2.5 inches. Each skirt is plain with no lights, and the driver side includes a block heater cutout. Sold as a kit with hardware included, it fits most Peterbilt 579 makes and models. Upgrade your exhaust system with this reliable and versatile kit for enhanced performance and functionality.