SD45R

The EMD SD45R is a diesel-electric locomotive rebuilt from EMD SD45 units by the Southern Pacific Transportation Company. The rebuilding program began in 1984 and focused on upgrading the original SD45s to improve reliability and performance. Key modifications typically included the replacement of the original D77 traction motors with D78 or D77B traction motors, and the installation of a new air brake system. Some units also received upgraded electrical components and improvements to the cooling systems. The prime mover, an EMD 20-645E3, was generally retained.

These locomotives retained the distinctive flared radiators characteristic of the SD45 series. The SD45R designation indicated the locomotive's rebuilt status. Southern Pacific used these locomotives extensively in freight service across its network. The rebuilding program was a cost-effective way to extend the service life of existing motive power rather than purchasing entirely new locomotives. While the exact number of units rebuilt varies slightly in different sources, the program encompassed a significant portion of the Southern Pacific's SD45 fleet. These locomotives served for many years, contributing to the railroad's operations until the eventual merger with Union Pacific.