I have 2002 4x4 Dodge 2500 Cummins with a six speed. For a couple months now my clutch has been hard to push down. When the truck is off the cluch pushes rather easily, but as soon as you start it its hard to push. Its doesnt shift hard though. My dad has a 2001 Ram 2500 Cummins and you can almost push the pedal with your fingers. Some people told me it may be the master/slave cylinder. But one guy told me it seems like something else because it dont do it all the when its off.