1980 merc 70. I have rebuilt the water pump on my lower unit. There is a considerable amount of wear on the driveshaft where the bottom seal meets the driveshaft. The oil was dirty but free of water when I removed it. In the future, if there is too much wear on the driveshaft and am getting water in oil, are there any opportunities to repair the driveshaft. They are kinda expensive to buy. $$$$$$$$$$$