So I was out on the water 2 weekends ago and doing about 3000 RPM just cruising along then all of a sudden, the engine revs high. I throttled down and turned the engine off. I noticed the smell of burnt rubber and thought the prop shaft rubber spun. I had to be towed in. Thank goodness for TowBoat US membership. Anyways, after getting the boat back home, it turned out it wasnt the prop or the coupling. I removed the outdrive and found the problem to be a broken upper shaft. This caused damage to the upper housing requiring it be replaced. I will be replacing the shaft along with all of the bearings as well. I see there are three different size thrust bearings/washers available. What is the reason for the different size thrust bearings/washers? Can I replace all of the components (shaft, bearings, etc.) with exactly the same that was in the housing before? I'm desperate. Please help.