'Does all 2004 RAM 1500 Hemi have MDS'?

Not all 2004 RAM 1500 models equipped with the Hemi engine have the Multi-Displacement System (MDS). The MDS feature was introduced in the 2005 model year for the 5.7L Hemi engine, allowing the engine to deactivate four cylinders under light-load conditions to improve fuel efficiency. Therefore, if you have a 2004 RAM 1500 Hemi, it will not have MDS.