I ran my 16 foot Aqua-Craft today. It has an olds-mo-pile 455 in it with a few aftermarket parts in it, nothing fancy. Besides for a couple of small leaks it ran pretty good. The engine runs excellent, but the gear box seems to be making a little noise. At idle it rattles a little bit, at full throttle, there is this strange noise that seems to be coming from the back of the boat around the prop area. The prop is a three blade, and appears to be brass. Do these things make noise regularly? Any ideas would be greatdevil.