Lower unit broke several teeth had to rebuild. I have run into a problem never seen before. I replaced the regular gears with the Sierra heavy duty gear set which include pinion gear to match. I also have the OMC tool for setting tolerance from drive shaft bearing housing assembly to pinion...
How do I determine what size the lower gear case is. When I look up the part for water pump it wants to know 20" Standard Rotation or 25 - 30" Standard Rotation:)
