Home Postcode finder SA Mount Mary Mount Mary postcode SA Mount Mary 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 Mount Mary business listing Be the first listing in Mount Mary Common questionsWhat is the postcode for Mount Mary?Mount Mary, SA has the postcode 5374.What state is Mount Mary in?Mount Mary 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 Mount Mary. Browse other postcodes in South Australia, or widen the search to every Australian postcode.