Home Postcode finder SA Buchanan Buchanan postcode SA Buchanan is a locality in South Australia covered by postcode 5374. Postcode 5374 State or territory South Australia (SA) Region Sa Subs Near 1 Add a free Buchanan business listing Be the first listing in Buchanan Common questionsWhat is the postcode for Buchanan?Buchanan, SA has the postcode 5374.What state is Buchanan in?Buchanan is in South Australia (SA).Does postcode 5374 cover more than one suburb?Yes. Postcode 5374 covers 15 localities, so the postcode alone does not identify Buchanan. Browse other postcodes in South Australia, or widen the search to every Australian postcode.