The DF class were built by GM in Canada and introduced from 1979. In 1990's were upgraded with turbo etc to GT22 MC. Trains to and from Napier are quite erratic in length with timber products being the main traffic.
Trains on 3' 6" (1.067m) track from Whangarei to Bluff with virtually heritage rebuilt EMD and GE locomotives still the mainstay power. The network was privatized in 1990's and operated by Toll until 2008 when state owned KiwiRail was established.