Changed my mind on the Kidd build, what I am now thinking is defence became a big political issue in Australia in the mid 70s following Indonesia's bloody annexation of East Timor in 1975.
Basically the Australian Federal Election, following the dismissal of the Whitlam Government on the 11 November 1975, was held on 13 December, with Indonesia invading Timor on 7 December and the Balibo Five (Australian, New Zealand and UK journalists) being killed by the Indonesian military on 16 December. What happened in reality is neither the invasion or the murder had much political impact in Australia at the time as both parties put relations with Indonesia above any violations that may have occurred in the annexation. Now if the date for the election was stretched out to say mid January 1976 then the murder of the journalists could have made the invasion an election issue, forcing the caretaker government to take action against Indonesia and souring relations between the two countries going forward. This souring of the relationship with our closest neighbour in turn would have made defence, or more to the point low defence spending and hence reduced capability, a political issue which it had not been since the early 60s when opposition pressure (and some genuine fear) basically forced the order of new strike aircraft (the F-111) after much dilly dallying, the retention of the fixed wing FAA and the expansion and re-equipment of the army.
So now in 1976 the new government reviews the previous governments selection of the Oliver Hazard Perry Class FFG over the (on paper) more capable Type 42 Destroyer as a replacement for the cancelled indigenous DDL project that had been intended to eventually build up to ten destroyers to replace the RANs Daring Class (and maybe the Battle Class) Destroyers and River Class Destroyer Escorts. The previous government had announced their intention to order two OHPs despite the design being rated as inferior and incapable of meeting requirements as the preferred Type 42 was not available with the preferred Tartar Missile system. In the real world the new government approved the selection of the OHP and confirmed the order for two of them, this was followed by an order for another pair and then the local build of a third pair some time later. In my imaginary world the review, in the light of our worsening strategic situation and the fact defence is now an issue, both designs are found to be unsatisfactory, the requirements are reviewed and a new project is started looking for a more capable destroyer as opposed to a frigate to replace the already decommissioned Battle Class Destroyers as well as the in service Daring Class Destroyers for a total of five ships to bring destroyer numbers up to eight.
The designs considered for this new project were the improved Batch III Type 42 about to be ordered for the RN, the Dutch Tromp Class FFG, the Italian Audace Class DDG and the US DDG-47. Notional designs were not considered as what is now called a MOTS solution was desired. The Batch III Type 42 while improved still was not entirely satisfactory and still lacked the desired Tartar system, the Audace was steam powered and no longer in production while the DDG-47 was highly developmental, not expected to be available until the mid 80s and hideously expensive. This left the Tromp as the best solution, requiring only a minor redesign to replace the twin 120mm with the preferred US Mk-45 5" gun. Australia was about to place an order for a pair of Tromps when Ingalls ship building made an unsolicited offer of the Spruance DDG design as ordered by Iran. Examining the new contender the RAN was extremely impressed with the capability on offer and recommended its selection to the government.
While the design satisfied all the requirements laid out by the RAN there was the issue of build and delivery with an Australian order to be tagged on the end of the USN Spruance program and also after the Iranian order. This actually made local construction the faster and preferred option rather than the overseas off the shelf buy that had been intended. At this point, none of the other designs were available in the desired timeframe either, which led to the FFG-7 being reconsidered but eliminated again when compared to the DDG-993 Class. Accordingly in October 1976 an order was placed for five DDGs with an option for another five, to be constructed at the redeveloped Cockatoo Island shipyard. Experts were brought in from Ingalls to assist in the design and construction of the redeveloped and expanded shipyard which would now be joined to the mainland by a massive hardstand built on reclaimed land. Block fabrication started in the existing building halls, shipbuilders travelled to the US to work at Ingalls to gain experience with building the design and designers also travelled to the US to work on the detail design of the Australian version of the ship.
The Australian version of the DDG-993 was very similar to the Iranian ships but with an expanded hanger for two Wessex or Sea King ASW helicopters, 44 missile Mk-26 launchers forward and aft (i.e. no provision for the 8" MCLWG), an additional pair of SPG-51 fire control radars, provision for the (in development) canister launched Super Ikara, provision for up to sixteen canister launched harpoon and up to four Phalanx CIWS. The first ship was laid down in 1978 and commissioned in 1982, subsequent vessels were laid down at twelve month intervals with completion through to commissioning reducing progressively from 48 months for the first to 30 months for the fifth ship which resulted in the government taking up the option for the additional five ships.