Home Postcodes by state SA 5473 Postcode 5473 5473 is the postcode for Gladstone, SA. Localities with postcode 5473GladstoneSA Postcode 5473 State or territory South Australia (SA) Localities 1 Council area Northern Areas Council area based on Australian Bureau of Statistics data (ASGS Edition 3), CC BY 4.0. Postcode 5472 · Postcode 5480