The SR axle should swap over but you may need to fiddle with the driveshaft if the ends don't fit properly.

Also consider swapping over the SR trailing arms if you're running un-reinforced gen I axles.

Based on the number of posts where an SR's rear axle has failed I'd say they last a long, long, long time. Mine personally have over 300K miles on them with only regular fluid changes. In fact the only one I recall hearing about failing was on a rig with 35's or 37's being abused hard down under (tracks going up hill if I recall correctly).

I'd bet you can count the number of failed axles in the US on just one hand. <img src="/forums/images/graemlins/kewl.gif" alt="" />

As for the front brakes, IIRC Grasscat/Michael swapped over Gen II's into his Gen I.