The CIM interface gear is 72 tooth, the stock gear weighs 1.6 lbs but with simple lathe work I shaved it down to .85 lbs. With more work it could lose quite a bit more. Overall the gearbox with the CIMs weighs in at 9.25 lbs. I am currently building a set for this year. The outside the box gear design was adapted from an idea that Greg Perkins concepted.
more on my gearbox was discussed
here