In 2000 LR Australia imported a production Defender 110" Tdi Hardtop from the UK and then altered to suit Australian Army fleet requirements. LRA handed it over for the ADF to evaluate... and later a supply contract was approved:

Update: 11.07.2008: 33 of these vehicles were bought by the Army in 2000, and a further 17 in 2004. They are slated as having a 10 year service life, which is significantly shorter than the Perentie that it serves alongside.

"Land Rover Australia has agreed to supply 33 custom built Land Rover 110 vehicles for use by the Australian Army. The vehicles will be built in Solihull, England, and are based on a Land Rover Defender 110 which uses the new 2.5litre, 5 cylinder turbo-diesel (Td5) power unit...

"LRA is very excited about working with the ADF - this is the first time since 1977 that the ADF has specified general-duty Land Rovers based on a production model," said John Skinner, Commercial Director, LRA.

"Land Rover vehicles built for the ADF under the Perentie (1984-92) and Bushranger contracts (1992-98) were specially designed 4x4 and 6x6 vehicles built at either Moorebank (Perentie) or Adelaide (Bushranger) and had different power units and transmission systems to the Solihull-built, Defender-based Land Rover 110 vehicles now commissioned. George Fowler, LRA engineering, who is responsible for the development of this latest production-based Land Rover 110, said the order was a breakthrough for LRA in the ADF vehicle procurement program.

"The ADF has decided to use a production vehicle which is designed for a ten-year period of service. This decision recognises the increased levels of reliability and durability of a Solihull-production Defender 110, with the new Td5 power unit.

"George Fowler and his team of engineers developed a concept vehicle, based on a production Land Rover 110, that was similar to existing Perentie and Bushranger Land Rover 4x4 vehicles in terms of driver control layout and ancillary equipment."

The article infers that

1. the ADF is attracted to the Defender Hardtop (Td5) even though its not built to have the long service life of the Perentie, i.e., the Defender costs much less per unit.
2. the ADF is attracted to the new generation 5 cylinder diesel power unit that comes with the "Solihull product" nowadays.

In late 2004 more information behind the Td5 Defender "general duties" came along. It turns out that in 2001 LRA sold off the first prototype/concept Tdi unit which had different sized side windows (NSW plated VDQ-254) at a local Moorebank auction yard.

LRA sold off the second "prototype Remediation Defender Hardtop" (vin SALLDBA87XA162467) at a Moorebank auction, 16th December 2004. "This was the Td5 variant and its interesting as it arrived in Australia having already been converted for another use by LRUK Special Vehicles (it carries an SV ident plate under the bonnet)". It was subsequently converted to the ADF configuration by LRA and looks identical to the 33 units purchased under the contract (See 2002 'in-service' pics below).