Sweet Talker
(1991, Bryan Brown, Karen Allen)
Set and filmed in South Australia. Brown plays a con-man who arrives on what I believe is a Bedford SB3 with Comair body. SYM275 was new to MTT Hobart, before moving to the local Mount Gambier operator:
Also seen is Deluxe Coachlines 206, a 1988 Austral DC122 Tourmaster. Deluxe Coachlines went out of business in 1990. They are credited at the end of the film:
(thanks wisp at the Australian Transport Discussion Board)