During the late 1950s to early 1960s, many older AB class locomotives were being withdrawn as they wore out and were replaced by locomotives displaced from other regions. With many engines still in relatively good condition, these engines were cannabalised following withdrawal to keep other engines going until they were either worn out or replaced by the new diesel locomotives then being purchased by NZR. This became a fairly common practice at the time; as the locomotives were of a standard design, parts could be taken from any engine to ensure another could keep running for some time to come.