Hey,
with PN Racing Mini-Z Stainless Shims Set [Parts # 700401] you can remove
one of the kyosho shims and use the M2 x 4.2mm x 0.2mm SS shims to tune
your Diff. in 0.2mm steps. about $4 a pack.
and the fit is Great.
the kyosho shims are 1mm ea. thats a lot of Tuning.