[attackdog]

Hey Vroom. I recently replaced the mirrors on my 01 Yukon w/ signal mirrors. The insert pieces had to be removed for the new mirrors. A friend of mine did the work for me, but looking at the mirror, under the insert is just the plastics of the mirror w/ some adhesive and 4 holes were the insert clips into. the inserts on my mirrors came off pretty easy.I don't think you will be able to tighten anything inside the mirror by removing the insert. Hope this helps.