1974 Mack Concrete Truck

The Mack R series is a line of Class 8 heavy-duty trucks introduced in the early 1960s by Mack Trucks. It replaced the very successful Mack B series models. R Model production ran for 40 years until the RD model was discontinued in 2004 and the RB and Mack D series 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.

The “U” and “DM” series were modifications of the “R” series. A short hood, and the shorter “bumper to back of cab” distance, made them useful in straight trucks and in semi-tractors used in congested cities, but caused the engine to intrude into the passenger compartment. To compensate the cab was offset to the left: the engine “doghouse” intruded into the passenger footwell but left the driver’s position intact.

The U was basically a short R, while the DM was an extra heavy duty version of the U often used in 6X4 construction trucks. Like the RMM, the DMM was all wheel drive, but had not only a short hood/offset cab, but also a set back front axle, requiring a model specific fiberglass hood/fender arrangement.