If I'm not mistaken, the R50's have the same front diff as the WD21's, which is an R200. There are TONS of WD21's on 33's, and larger, using stock differentials. I can't see that being a problem. You may have been reading about the Newer Xterra, and Frontier that have a 180mm diff, cased in aluminum, that's been known to grenade.
Oh, and the chances of you ruining a Nissan rear differential are slim to none.