Home Postcodes by state SA 5023 Postcode 5023 5023 is the postcode for 3 localities in SA: Findon, Seaton and Seaton North. Localities with postcode 5023FindonSASeatonSASeaton NorthSA Postcode 5023 State or territory South Australia (SA) Localities 3 Council area Charles Sturt Council area based on Australian Bureau of Statistics data (ASGS Edition 3), CC BY 4.0. Postcode 5022 · Postcode 5024