[lincpimp]

I do not have a savvy diff handy but I do not think that shim is needed?

Does the bearing race (outer part that remians stationary) touch the ring gear? If not then you are good to go. The X manual calls for the shim to be there, but that is for the plastic bulks, and it is likely there so you can remove it and place it on the other side to get the mesh right after something wears, or vice versa.