On 17 January 1968, "Sydney" departed Sydney on her ninth voyage to Vietnam. Meeting "Stuart" off Singapore on 25 January, the two ships visited Sattahip, Thailand on 31 January before continuing on to Vietnam. "Sydney" arrived in Vũng Tàu on 3 February, and departed the same day for home; arriving in Sydney on 16 February. "Sydney"s tenth voyage began on 27 March, with 1 RAR embarked for their second Vietnam deployment, and the destroyer escort "Parramatta" meeting the troopship off Singapore. The battalion was delivered to Vũng Tàu on 9 April, with 7 RAR on board for the return to Australia, where they arrived on 26 April. The eleventh voyage saw "Sydney", with the destroyer "Anzac" escorting, depart Brisbane on 21 May with 4 RAR aboard. The ships arrived at Vũng Tàu on 1 June, where the battalion was replaced by 2 RAR for the return voyage to Brisbane, which was reached on 13 June. After this voyage, "Sydney" underwent an extensive refit in which she was fitted with three new Favelle Favco-type cargo cranes and modified to carry six Landing Craft Mechanized (LCM (6)) on davits. 16 LCM were constructed for use with "Sydney", but half were put up for sale in the early 1970s. During September and October, "Sydney" temporarily resumed flagship duties, and participated in the amphibious warfare exercise Coral Sands. After the exercise, the troopship undertook a training cruise to New Zealand. "Sydney"s twelfth voyage was to deliver 9 RAR to Vietnam. The troopship sailed from Fremantle on 13 November, and met the destroyer "Duchess" off Singapore on 18 November. 9 RAR was delivered to Vũng Tàu on 20 November, while 3 RAR and a damaged de Havilland Caribou were loaded for the return trip, which concluded in Fremantle on 28 November.