I'm changing a 2.00:1 B2 drive into a B3, changing only the lowers. The B2 is stamped on the upper 2.00:1 and the B3's upper was stamped 2.20:1, what am I going to end up with?
I beleive they both use 1.50:1 upper gears, and the difference is in the lower, so I should end up with a 2.20:1 B3.
any help on this one?

I think the ratio will be the same as with the b2.

By looking at the chart in the attached link, it looks like they change the ratio in the uppers. They used 3 different ratios in the uppers.

With both lowers removed, spin each prop shaft 10 rotations and count the rotations of the vertical shaft. You will be able to tell if there is a different in the lower ratios.

http://www.mtboats.com/outdrivegearratios.html

thanks for that link, with that I was able to figure out what it would be.
Larry