Home Postcodes by state WA 6437 Postcode 6437 6437 is the postcode for 2 localities in WA: Leinster and Sir Samuel. Localities with postcode 6437LeinsterWASir SamuelWA Postcode 6437 State or territory Western Australia (WA) Localities 2 Council area Leonora Council area based on Australian Bureau of Statistics data (ASGS Edition 3), CC BY 4.0. Postcode 6436 · Postcode 6438