There are two 1/8" wide metal strips that run down each side of a wiper blade inside of a groove. Since I buy a 14"-16" wiper blade, the metal strips are too long. You could cut them down along with the wiper blade, but it is quicker to just reuse the orginal ones.
I am sure you could order a new arm and wiper blade from gmpartsdirect, but I can spend $10, or less, for just a wiper blade. They usually run in a groove along the top side of a wiper blade.
That is too big for mine and would not work. The total length of the arm that holds my wiper blade is about 13.75". Is that wiper blade on amazon.com what you have currently installed?