The components have long lead times for manufacturing and include hulls, axle and suspension systems, fire suppression systems, radiators, gun rings, insulation and hydraulics parts.
Thales Australia, formerly ADI, makes the 4x4 Bushmaster Protected Mobility Vehicle and components at its factory in Bendigo in the state of Victoria.
A statement by Minister for Defense Stephen Smith and Minister for Defense Materiel Jason Clare said the Thales manufacturing capability and the skills of the workforce are an important national security capability that the government wants to ensure remains viable.
The army acquired its first batch of 300 Bushmasters starting in August 2004 and delivery of the latest variants started in 2008.
Australia has around 700 Bushmasters, many of which are in Afghanistan and are credited with saving numerous Australian soldiers' lives, Smith said.
The Bushmaster is available in a range of variants including troop transport, ambulance, direct fire, mortar, engineer and command for application in combat and combat support roles.
Powered by Caterpillar 3126E ATAAC turbocharged engine, the vehicle is capable of carrying up to nine soldiers along with their equipment, fuel and supplies for three days, depending on the type of variant.
The potential order for more Bushmasters through the $15.5 million injection into Thales Australia is in addition to 101 units the government ordered in May.
In December the government announced that to retain the critical manufacturing skills in Bendigo it would explore the purchase of additional Bushmaster vehicles.
The $15.5 million "is the next step in that process," the statement by Smith and Clare said.
"Full approval to acquire additional Bushmasters will be dependent on Thales demonstrating an efficient, effective and innovative program to maintain core protected vehicle manufacturing skills at Bendigo and in successfully meeting technical performance, cost and schedule commitments in the development of the new Hawkei vehicle."
The 4x4, 6-crew, 7-ton Hawkei is Thales Australia's next-generation protected vehicle based on the Bushmaster.
The government announced in December that the Hawkei vehicle had been selected as the preferred vehicle for development and testing in Australia's search for an improved protected mobility vehicle.
Work on the Hawkei is being done under Stage 2 of the Manufactured and Supported in Australia option under LAND 121 Phase 4.
LAND 121 Phase 4 is a $1.5 billion project that seeks to provide up to 1,300 protected and unprotected light vehicles for the military.
But final government approval and orders for the Hawkei aren't expected before 2015 with production starting in early 2016, a Thales statement said.
Thales Australia has worked with Boeing, PAC Group and Plasan, as well as many Australian small and medium-sized businesses to develop the Hawkei, a report on the Thales Web site says.
The name Hawkei comes from the Latin name for the deadly adder -- Acanthophis hawkei -- which is native to Australia, Thales said.