SEOUL, Dec 8 (Reuters) - South Korea's Hanwha Aerospace said on Friday it has signed a contract with Australia to supply 129 Redback infantry fighting vehicles by 2028 in a 3.16 trillion won ($2.4 billion) deal. ($1 = 1,314.0400 won) (Reporting by Soo-hyang Choi, Ju-min Park Editing by Ed Davies)