Ensure good condition of the Sterntube bore in which the bearing will be fitted. Measure well to calculate the outside diameter of the new bearing – to be machined on site. Note that the stern tube bore may need machining or repairing. Check and double check the orientation of the bearing before fitting. There are external and internal features which must line up. Check the condition of the shaft, any machining here will require machining a smaller than anticipated bearing inside diameter. Cleanliness, lubrication and removal of sharp edges is key when hydraulically pushing up a white metal bearing. Any pickup on the bearing outside diameter could ruin your new bearing (and damage the stern tube too).