Mopar 5303 2221AA, Engine Expansion Plug

Note: This plug is used in place of the MDS Valve on engines that don't have a Multiple Displacement System (MDS). Most 5.7L engines from 2003-08 had MDS that shut down some cylinders to conserve fuel. Four of these plugs are used with two sets of Tappets 312-53021720AE to convert a 5.7L engine to non-MDS. Ideal for engine conversions in street rods & muscle cars that don't use MDS.