If you use parts from a V6 Terrano or Pathfinder is very straight forward. The VG30E uses a different bell housing pattern and completely different gearbox and transfer case to the Z24. The standard Pathfinder diffs are very strong you can check on the plate under the bonnet. Rear diff should be a HG48 LSD the same basic diff used in Nissan Patrols, virtually indestructible. Below is a full list of the parts needed for the conversion.
VG30E motor with all accessories
Gearbox and transfer case to suit V6
Radiator to suit V6
High pressure EFI fuel pump
Change all fuel hoses to suit high pressure
Exhaust system with cat converter
ECU and wiring loom
Air box with airflow meter
What you don't want is a VG30 motor from anything but a pathfinder or navara because they have the wrong air intake and a V6 gearbox auto or manual has a bigger output shaft than the Z24 gearbox so they wont mate up to the Z24 transfer case. If you source the right parts it is a bolt together job with no cutting or hacking required. Yes I have done the conversion so all of this info is correct.
I am selling a complete VG30E conversion if any of you are interested. After doing 95% of a V6 conversion to my Pathfinder I have decided that I need a diesel powered 4x4 to do some of the trips I have planned for the near future so I have purchased a YD25 with 37000kms from latest model navara. If any of you are interested in buying the complete conversion send me an email or ring 040 784 9775 probably looking at $2500- for the whole lot, the wreckers ask $1650- just for the transmission. I am located in Colac Victoria