Abstract: The present invention provides a structural member of a multi-alloy monolithic extrusion comprising a first aluminum alloy and a second aluminum alloy; wherein the first aluminum alloy is metallurgically fused to the second aluminum alloy. In another aspect of the present invention, an extrusion method is provided including the steps of providing a first billet and at least a second billet; machining the first billet to form a first substantially flat surface; machining the second billet to form a second flat surface; positioning the first flat surface of the first billet adjacent to the second flat surface of the second billet; welding at least a portion of the first billet to the second billet to form a third billet; and extruding the third billet to form a monolithic multi-alloy structural member.