Nine K class were delivered in 1966/67 to operate services on the 657-kilometre (408 mi) Eastern Goldfields Railway from Perth to Kalgoorlie that was being converted to standard gauge. After initially working construction trains, in November 1966 they began working wheat trains from Merredin to Fremantle and once the full line was opened began working services to Kalgoorlie and Esperance.
In January 1966, K201 became the first locomotive to travel across Australia. It hauled freight trains from Brisbane to Melbourne, before being hauled for the rest of the journey. It passed through five states, travelled on six railway systems and required a change of bogies at Melbourne, Port Pirie and Kalgoorlie.
Goldsworthy Mining Ltd had purchased six similar locomotives, and after having one destroyed in an accident, purchased K202 with K210 ordered as a replacement. In July 1986 Goldsworth Mining purchased K203.