Outer Limits 4x4 Board

I'm in the process of shaving my GU diff I run 4.6 diff ratios. I have a spare 4.1 diff centre. I would rather not pull the 4.6 centre out unit needed. So if I shave the diff using the 4.1 center as a guide do I need allow any extra space for the 4.6 gears if so how much ?
thanks Feral

There both the same diameter. There all 233mm or 260mm. It's all in the tooth count.

Perfect thanks for that.
Let the shaving commence.