ok mate first, u dont need to change diff, u cant either change the centre to an lsd, change both centre and diff gears so changing from single spinning center to an lsd and changing diff gears from 3.08 to 4.11 gears usally get gears from a nissan pintara (r31 skyline just lower model) i would suggest change both. diff center off ebay 300-400 reco and gears u can pay from 150-400 depending try get gears that are out of a low km car as they tend to whine. or better brand new ones. remember ebay is a very good friend
_________________
Previous cars
1995 ef futura - nothing special
2003 xr6 turbo 5 -speed 307rwkw