Transmission kit 2005-2010 6 Speed Allison 1000-2400 series. Duramax Diesel Chevrolet, GMC Diesel/Gas Trucks Heavy Duty, Street, Show & Competition. For 5 Speed Allison use Allison SK. Ford and Lincoln Mercury THIS KIT FITS ONLY 6 SPEED UNITS!!!!! WILL NOT FIT 5 SPEED UNITS!!!!!