Question of how and why the 3s blx diffs may need shimming?How to test if diff needs shimming? I assume you hold diff assy in hand and spin ring gear and if it binds in places, diff needs shimming. Is there a shim kit to buy of a different assortment of shims? Any videos that may be helpful? Finally, where to place the shim, behind or in frt of bearing? Thanks guy's!