Home Postcodes by state SA 5604 Postcode 5604 5604 is the postcode for Port Neill, SA. Localities with postcode 5604Port NeillSA Postcode 5604 State or territory South Australia (SA) Localities 1 Council area Tumby Bay Council area based on Australian Bureau of Statistics data (ASGS Edition 3), CC BY 4.0. Postcode 5603 · Postcode 5605