[Overdriven]

It would be pretty easy to figure out how big of a spur gear you can put on your CD without it hitting the top plate. BrianG's page has a gear calculator, just need to measure the amount of clearance you have. Another option is a custom top plate that has an opening (slot) in it for the spur gear. The top plate would have to be wider to accomodate the spur gear slot and still connect the diff mounts together, but it would do the job and support both front and rear brake cams.