This Sierra 1819521 manifold is a direct replacement for the 4.3L V6 MP#611447. This manifold is made from high quality materials and is designed to fit the Sierra 4.3L V6 engine. This manifold is a great option for those who are looking for a high quality replacement manifold. This Sierra 1819521 manifold is a direct replacement for the 4.3L V6 MP#611447. This manifold is made from high quality materials and is designed to fit the Sierra 4.3L V6 engine. This manifold is a great option for those who are looking for a high quality replacement manifold.