The Saurer 4K 4FA is an Austrian armoured personnel carrier with caterpillar tracks. It was later replaced by the Steyr 4K 7FA G 127. It went into production in 1961. In 1956, Osterreichische Saurer-Werke of Vienna (which was taken over by Steyr-Daimler-Puch AG in 1970) started development of an armoured personnel carrier. The first prototype, the 3K 3H, was completed in 1958 and the second, the 4K 3H, the following year. They are both powered by a Saurer 3H 200 hp diesel engine.