Taa Dc-9/b-737
Actually TAA had ceased to exist by 1989, having become "Australian Airlines" in 1986.
Additionally, Australian introduced the B737-300 before Ansett did.
Going Boeing, maui and Buster have all hit the nail on the head.
Ansett would probably have been better waiting for the B737-300 as well, but their fleet decisions were not necessarily made on purely commercial grounds. Perhaps the joint Chairman of TAA/Australian was unable to get a lunch date with (former US President) Jimmy Carter.