Repair or upgrade the transmission cooling in your 2020 Chevy/GMC 3.0L Duramax with Direct-Fit Transmission Coolers & Lines. The increase in fluid capacity and core volume will offer enhanced cooling efficiency with an aftermarket transmission cooler. The cooler lines are available in factory replacement or performance durable braided hoses with billet -AN fittings. There are performance thermal bypass valves for some transmission coolers that can take the place of the troublesome factory thermal bypass valve. Mishimoto, Dorman, BD-Power, and more top-notch manufacturers are available.