Pack of 8 Square Ignition Coils for 99-09 Cadillac Escalade Chevy Avalanche Silverado Suburban Tahoe GMC Topkick Savanna Sierra Yukon 4.8L 5.3L 6.0L 8.1L H6T55171ZC 3859078 C1208 UF-271 DIRECT REPLACEMENT/ UPGRADE over your original stock coils. We only use the highest grade materials. This makes our product durable and reliable under extreme conditions while providing High Electrical Resistance, strong Spark from plugs, and being resistant to Corrosion and Abrasion IGNITION COIL PACK for, 4.8L 5.3L 6.0L 8.1L, C4500 Topkick, C5500 Topkick, C6500 Topkick, C7500 Topkick, C7500 Kodiak, Silverado 2500 HD, Silverado 3500, Savana 3500, Sierra 1500, Sierra 1500, Sierra 2500 HD, Sierra 3500, Avalanche 2500, Silverado 2500 HD, Silverado 3500, Suburban 2500, Savana 2500, Sierra 1500 HD, Sierra 2500 HD, Sierra 3500, Yukon XL 2500, Escalade, Sierra 2500, Express 3500 Our replacement ignition coils are easy to install with the highest quality copper. Each coil is design for specific application, low-emissions, and high energy output. Other Part Numbers: D581, 5c1083, E226, 52-1618, Ic400, 12558693, H6t55171zc IMPORTANT: Please check interchangeable part numbers and/or verify if car year, make, model, sub-model, engine size and VIN number matches before purchasing products. The manufactures of the vehicles changed their coils mid-year so your vehicle might need the ENAIC350808 (Square) or ENAIC121308 (Round) Coils depending on what month the vehicle was made in. Eliminate misfire Direct installation into vehicle Increase horsepower Stronger throttle response Durable as they come Custom-made for the road Fit OE equipment with ease Tested in real life situations Most coils comepre-greased