The Mack R Model was a Class 8 heavy-duty truck first introduced in 1966, by Mack Trucks, to replace the very successful Mack B Model. Its production ran for 40 years until the RD model was discontinued in 2002 and the RB and DM models were discontinued in 2005. The first R models introduced were powered by Mack Thermodyne diesel and gasoline engines. In 1973 the R cab was given a makeover to include a deeper rear wall for more room and a new dashboard design.