I must be fortunate having traveled in an Ansett Sandringham as a child and later in a TAA Sunbird Service Catalina!
B772. I'm sure you meant the Dash 7? The DHC8-100 (PW120 or PW121 engines) first deliveries were 1984 and DHC8-200 (PW123 engines) in the 1990s.
Lucky they didn't buy the Dash 7 - it wasn't exactly an outstanding financial success........