no. running 4wd would never wear it out unless wheel rolling radius was out.

aside from 32s (maybe not even the V-Spec 32s, i forget), ALL skylines run permanent 4wd, only a very little bit maybe, but some power to both wheels all the time. done for stability at high speed in a straight line, etc etc.

so they apart from 32s, it is running them totally RWD (if you was wheelspinning and doing burnouts that is) that would (albeit slowly) wear the centre diff out.

but on the cossie setups that ive seen, the 4wd hasnt been active (ie it doesnt change torque split on its own, you do it), so it should be able to be set from nothing to full, so no wear on centre diff regardless.