These cars were built by Pacific Car and Foundry in Benton, WA. The R-70-20 designation stands for a reefer with 70 ton capacity. The 20 designates with was the 20 design in the builders reefer series. The cars are a direct derivative of the PFE reefer design. They represent the last major release of this design of cars. In 1969, 1,200 of these cars were delivered, with an additional 1,200 delivered in 1970. Initially the cars were delivered in PFE lettering.