http://www.duramaxmarine.com/pdf/CutlessBearingMS.pdf

I'm not sure which shaft diameter you have; however, it sounds like you should have a 1-1/8" shaft -- looks like a "BEND" model would be 44.5 mm in outside diameter of the bearing.

What did you buy and where?

Have you contacted the boat manufacturer to discuss the issue?

I'm assuming you have a naval brass and not a synthetic model...