Home Postcode finder SA Muston Muston postcode SA Muston is a locality in South Australia covered by postcode 5221. Postcode 5221 State or territory South Australia (SA) Region Sa Subs Near 2 Add a free Muston business listing Be the first listing in Muston Common questionsWhat is the postcode for Muston?Muston, SA has the postcode 5221.What state is Muston in?Muston is in South Australia (SA).Does postcode 5221 cover more than one suburb?Yes. Postcode 5221 covers 3 localities, so the postcode alone does not identify Muston. Browse other postcodes in South Australia, or widen the search to every Australian postcode.