Home Postcode finder SA Halidon Halidon postcode SA Halidon is a locality in South Australia covered by postcode 5309. Postcode 5309 State or territory South Australia (SA) Region Sa Subs Near 2 Add a free Halidon business listing Be the first listing in Halidon Common questionsWhat is the postcode for Halidon?Halidon, SA has the postcode 5309.What state is Halidon in?Halidon is in South Australia (SA).Does postcode 5309 cover more than one suburb?Yes. Postcode 5309 covers 4 localities, so the postcode alone does not identify Halidon. Browse other postcodes in South Australia, or widen the search to every Australian postcode.