Home Postcodes by state SA 5173 Postcode 5173 5173 is the postcode for 4 localities in SA: Aldinga, Aldinga Beach, Port Willunga and Silver Sands. Localities with postcode 5173AldingaSAAldinga BeachSAPort WillungaSASilver SandsSA Postcode 5173 State or territory South Australia (SA) Localities 4 Council area Onkaparinga Council area based on Australian Bureau of Statistics data (ASGS Edition 3), CC BY 4.0. Postcode 5172 · Postcode 5174