This is a custom built 16" extention box I had built by a local machine shop. The box is made out of 1/2 inch aluminum plate. The box has two arms that extend into the boat. The engine mounts directly to the arms using the mercruiser racing solid front motor mount. This makes this box all one unit and extremely strong, it can handle 1800+ HP. Comes with a custom fabricated 16 inch extended input shaft. The box has mounts for external steering cylinders and fittings welded through the box for hydrolic lines. It has mounts inside for trim and trim tab pumps. The box is in good shape just needs to be repainted. I have over $4000 invested in having this built. I'm selling this because I've converted the boat to outboards. Buyer responsible for shipping costs, it will be sent by yellow freight. E-mail me for shipping estimate.