Home Postcodes by state QLD 4373 Postcode 4373 4373 is the postcode for 3 localities in QLD: Killarney, The Falls and The Head. Localities with postcode 4373KillarneyQLDThe FallsQLDThe HeadQLD Postcode 4373 State or territory Queensland (QLD) Localities 3 Council area Southern Downs Council area based on Australian Bureau of Statistics data (ASGS Edition 3), CC BY 4.0. Postcode 4372 · Postcode 4374