The "splined" driveshafts are susceptable to excessive wear and vibration if not aligned correctly. Just replacing the shims in the old location isn't correct, as the slots in the bed plate and motor mounts require precise alignment to prevent expensive repairs.. Our Alignment tool is manufactured from precision ground and polished 10/18 Steel with a specification of + zero and -.0005". This close tolerance is necessary to slide through the pump bearings, yet maintain a close tolerance fit so the driveshaft tool doesn't sag or drop during the alignment process. THIS TOOL REPLACES POLARIS OEM #2871343. Fits all Polaris watercraft from 1994- 2004, except Octane & MSX series, and Hydrospace watercraft. Excellent for Zodiac,Williams and other Weber based watercraft.