Home Postcodes by state SA 5091 Postcode 5091 5091 is the postcode for 3 localities in SA: Banksia Park, Tea Tree Gully and Vista. Localities with postcode 5091Banksia ParkSATea Tree GullySAVistaSA Postcode 5091 State or territory South Australia (SA) Localities 3 Council area Tea Tree Gully Council area based on Australian Bureau of Statistics data (ASGS Edition 3), CC BY 4.0. Postcode 5090 · Postcode 5092