25 hp 2006 4-stroke

[hood54]

Manufacturer: Mercury Marine
Serial Number: 0R181593
Model Group: 25/30 EFI (3 CYLINDER) 4-STROKE
bearing replacement under water pump up or down for cone position. how much to shim?

[boats.net]

That is pinion height shims and will need a service manual and special tools to shim properly.