If you are fitting stainles nuts on your axle, make sure they are made of a high tensile grade of stailess. Normal Stainless (such as 316L) is not a tensile material and may come loose. Another problem with stailess steel is that it is attacked by chlorine compounds (such as road salt).
Its far better to use chrome plated nuts if you are worried about finnish.
The standard nuts on your MZ are either cadnium or passivated zinc plated. This material acts as a sacrificial layer, corroding itself and helping the steel underneath to risist corrosion.
See this article
http://www.corrosion-doctors.org/Forms/scc.htm on the subject.
Keith