For most people, the part I installed tonight is the single most recognizable identifying mark of a modified Zenith 601XL or 650. The upright doubler is right above the wing on each side and can be seen at a distance. With this installation, I have completed the center spar and the main parts that hold it in place. I just have a few additional modifications that tie into the seat pans and fuselage sides, and my modificaitons will be complete!
