PartsW 4 Pc Suspension Kit for Chevrolet Silverado & GMC Sierra 1500 & 1500 Classic RWD Models Upper & Lower Ball Joints RWD Models W/ Front Coil & Rear Leaf (2004-2007) Undergo impact, wear, and fatigue testing to help ensure quality and durability Advanced corrosion protection against the harshest conditions / Precision-made performance and additional strength Designed with PREMIUM quality materials for exceptional performance, reliability and peace of mind Dust boot is re-installed and permanently attached to reduce contamination, and increase durability and service life