Home Postcodes by state WA 6476 Postcode 6476 6476 is the postcode for Gabbin, WA. Localities with postcode 6476GabbinWA Postcode 6476 State or territory Western Australia (WA) Localities 1 Council area Mount Marshall Council area based on Australian Bureau of Statistics data (ASGS Edition 3), CC BY 4.0. Postcode 6475 · Postcode 6477