The Z597-D is an active model in the U.S., but I can't speak for Australia as those decisions are made by the Toro International Division and it's Australian distributor and dealers. The Z Master 580-D models are built on a different frame than the Z Master Z597-D, are powered by a Kubota 25hp diesel engine, possess a host of different features and specs, and as a result are priced lower than the Z597-D series. In the States our product hierarchy based upon features/performance/price points would be Z580-D, Z597-D and Groundsmaster 7200 Series. Again, this may be different outside of the U.S.
The GM7200 drive wheel stance is the same for either 5' or 6' decks. There are three deck options, 62" Guardian Recycler, 72" Guardian Recycler and 72" side discharge. You can check out the features of all machines by visiting our website www.toro.com
-The Toro Company