Home Postcode finder SA Rocky Plain Rocky Plain postcode SA Rocky Plain is a locality in South Australia covered by postcode 5381. Postcode 5381 State or territory South Australia (SA) Region Sa Subs Near 1 Add a free Rocky Plain business listing Be the first listing in Rocky Plain Common questionsWhat is the postcode for Rocky Plain?Rocky Plain, SA has the postcode 5381.What state is Rocky Plain in?Rocky Plain is in South Australia (SA).Does postcode 5381 cover more than one suburb?Yes. Postcode 5381 covers 9 localities, so the postcode alone does not identify Rocky Plain. Browse other postcodes in South Australia, or widen the search to every Australian postcode.