Home Postcode finder SA Mount Barker Junction Mount Barker Junction postcode SA Mount Barker Junction is a locality in South Australia covered by postcode 5251. Postcode 5251 State or territory South Australia (SA) Region Sa Subs Near 2 Add a free Mount Barker Junction business listing Be the first listing in Mount Barker Junction Common questionsWhat is the postcode for Mount Barker Junction?Mount Barker Junction, SA has the postcode 5251.What state is Mount Barker Junction in?Mount Barker Junction is in South Australia (SA).Does postcode 5251 cover more than one suburb?Yes. Postcode 5251 covers 6 localities, so the postcode alone does not identify Mount Barker Junction. Browse other postcodes in South Australia, or widen the search to every Australian postcode.