Justin,
We actually run a lot of equipment from everywhere. Some are British (the XPT passenger service run by the NSW gov't is based on the British Intercity 125 technology (but manufactured here, with mods). Early diesel/electrics were based on US prototypes, with some fully imported. Passenger stock (long distance) is based on US design but locally produced. Railcars (in the 40's - 60's were based on US designs with Bud railcars used by Victoria and South Australia, and Victoria producing their own version of the Doodlebug. All suburban stock is designed and manufactured here. The last 20 years has seen loco's designed and manufactured here as well. They were (slight rumour) going to use the French TGV technology for fast interstate trains, but that never got off the ground, especially when the Intercity 125 technology never goes any faster that 50!