the shims on the side of the diff? between the bearings and the housing? NO!! don't touch those.
i'm assuming you have the minispool installed at this point and you've put the axles back into the tubes and they are seating properly in the splines in the minispool. you need to shove! the axle and then push the c clip in. if you don't have a buddy there use a ratcheting tow strap to pull the axle in.