Home Postcode finder WA Marradong Marradong postcode WA Marradong is a locality in Western Australia covered by postcode 6390. Postcode 6390 State or territory Western Australia (WA) Region Wa Subs 2 Gsr Add a free Marradong business listing Be the first listing in Marradong Common questionsWhat is the postcode for Marradong?Marradong, WA has the postcode 6390.What state is Marradong in?Marradong is in Western Australia (WA).Does postcode 6390 cover more than one suburb?Yes. Postcode 6390 covers 11 localities, so the postcode alone does not identify Marradong. Browse other postcodes in Western Australia, or widen the search to every Australian postcode.