This bracket was on ALL 1925-1929
big twins that left the factory. It is not an option or an accessory.
Its function is to keep the carburetor and manifold from rotating downward
via gravity and vibration. As you can see in the picture at the bottom,
it is simply wedged in between the fins and the carb/manifold joint
sits in the cradle in the middle. Easy to install and important to have.