Repair or upgrade the transmission cooling in your 2003-2004 Dodge 5.9L Diesel with Direct-Fit Transmission Coolers & Lines. Get performance braided hoses with billet -AN fittings or factory replacement cooler lines for your vehicle. There are performance thermal bypass valves for some transmission coolers that can take the place of the troublesome factory thermal bypass valve. Get increased cooling efficiency with an aftermarket transmission cooler that has a greater fluid capacity and core volume. Industry-leading brands such BD-Power, Mishimoto, Dorman, and more are offered.