In the 1800s and early 1900s, A lot of forging was done. This means forming the part by force and pressure. Wrenches are still made this way. Gun parts, machine parts, all were or had forged parts. The late 1800s the forge was almost as fast as the punch press. In addition, it toughened the steel. If the throttle linkage were made from Cast Iron it would have probably broken years ago. That goes for the forged fender braces as well. Hope this helps.
Terry