One of the best things you can do for your 2003-2004 Ram 5.9L Cummins build is adding on some aftermarket injector lines to your fuel system. Aftermarket Injector lines take your rig to the next level with improved fuel delivery and efficiency so you can get the most out of your engine. Ram Cummins Fitments: 2003, 2004 Ram 5.9L Cummins.Submodel Fitments: Tradesman, Laramie, Laramie Longhorn, Big Horn, Limited, Lone Star, Power Wagon.Some exceptions apply, please see individual product pages for specific fitments.