hmm....my 8ight diffs did not come with the inside shims for the spyder gears....on my lst2, the stock diffs did NOT have the shims either, but I believe Losi started putting the shims in with diff rebuild kits after that....I have used them both with, and without the shims (on the lst2) and can tell no difference...now the outside shim (or two) do make a difference as far as ring/pinion mesh go...