I replaced my PSS seal on my 92 Hunter30, last year. The diameter of the shaft was 1 inch. The hardest part was breaking free the shaft from the transmission. Little brute force was used, but once moving the shaft slid back far enough to pull out the old unit and replace with the new. My old unit did not have the nipple for water to exit. With this new unit, I had to add a hose which goes to the bilge. Though the PSS instructions say to raise the hose to 3 (?) feet above the water line, I do not have that much room. Up to this point, it has not flushed out but I know under extreme power it will. Just something to keep in mind.