I am thinking about installing a PSS shaft seal over the winter. The shaft on our 1989 Catalina 30 is 1 " in diameter (I think) but I don't know the dimension of the stern tube (what is this anyway) . Does anyone know what is the dimension of this tube? The price of the PSS shaft seal is under $200 but how much is the installation ? or can I do it myself. Any info would be great.ThanksCM