I have a few nsr's and an ns400 and want to clarify the interchangeability of nsr crank's. I know there are differences in mc18 MK2, mc21 and mc28 but are they interchangeable? Different crankwebs, flywheel etc? What would be required to put a 28 crank in an r5k if it's possible? I have all these and an r2j which I understand is quite different, and just want to know the finer details of each. Thanx for any input/ links.