I have several here in front of me...2 in peices and one that was together. The two that are apart have what I belive to be (and is called in a manual) a shim. Now my question is when to shim, why to shim and such. Also, back to gear lube, I was under the assumption that you used normal gear lube with an additive. Someone else has said, you can only use limited slip gear lube. Whats the answer there?