Got the hoizontal Stab off the wall where it has be hanging for years to prep for paint. I knew from a post by another builder that the hinge mount bolt holes needed to be reamed to full size. He had to dtill out the rivets and remove the mass blance fitting to get his reamer in to the hinge fittings, so I was anticapating the same. Fortunately my right angle drill attachment was able to do the job without removing the fitting.