Canadian Pacific originally purchased their 72–strong fleet of RS–18s back in 1957 and 1958 over two batches, numbered 8729-8748 and 8749-8800. After over 20 years of reliable service, the CPR sought to extend the lives of their venerable 251B–powered locomotives, as a means to provide a reliable, efficient roadswitcher for branchline and regional services through the 1980s and 1990s. The RS–18 – already a fairly reliable first–generation model – was chosen to fulfill this important role
