HP Autowerks supplied the Output shaft seal with my Wavetrac diff. That's a good thing because it was pretty tough to get them out
I saw no need to replace anything else.
'09 E93 M3 6MT, H&R sports, VMR710 19x9.5+22f 19x11+25r, Michelin PSS, VF540, AA TPs
'09 Z4 sDrive35i, Deep Sea Blue Metallic, DCT, Premium Pkg, Ivory Leather pkg