You're looking at a NEW Transgo Allison shift kit for the 2001-2005 Chevrolet & GMC HD trucks, diesel or gas. This heavy duty kit corrects the common problems with these transmissions; goes into neutral under load, 3-4 slip, burned C2 or C3 clutches, sticks in one gear, won't move after extended parking, loss of pump prime. This kit includes smart clutch control valves for increased durability and Short-Crisp-Smooth-upshifts and kickdowns. This kit also reduces trouble codes. This is the most complete shift correction kit available and definitely the most reputable.