This air brake valve fits all Mack MC model trucks as well as Mack MR/MRU model trucks, directing compressed air to the brake chambers to manage braking response across the chassis. It is sold individually as one each and is built as a replacement for these Mack applications.Interchanges:Mack 4379-RD551250Mack 4379-RD552150FeaturesAir brake valve, part number RCV-1204OEMFits all Mack MC model trucksFits all Mack MR/MRU model trucksSold individually, one eachTech SpecsSell Pack: 1 EachFitment: All Mack MC models, All Mack MR/MRU modelsUsed in this Truck Cab modelHeater & A/C Parts & Diagrams