Home Postcodes by state SA 5731 Postcode 5731 5731 is the postcode for 9 localities in SA: Coopers Creek, Cordillo Downs, Durham Downs, Innamincka, Leigh Creek, Lyndhurst and 3 more. Localities with postcode 5731Coopers CreekSACordillo DownsSADurham DownsSAInnaminckaSALeigh CreekSALyndhurstSAMerty MertySAMoolawatanaSAWitchelinaSA Postcode 5731 State or territory South Australia (SA) Localities 9 Council area Unincorporated SA Council area based on Australian Bureau of Statistics data (ASGS Edition 3), CC BY 4.0. Postcode 5730 · Postcode 5732