Home Postcodes by state SA 5631 Postcode 5631 5631 is the postcode for 2 localities in SA: Cockaleechie and Cummins. Localities with postcode 5631CockaleechieSACumminsSA Postcode 5631 State or territory South Australia (SA) Localities 2 Council area Tumby Bay; Lower Eyre Council area based on Australian Bureau of Statistics data (ASGS Edition 3), CC BY 4.0. Postcode 5630 · Postcode 5632