Well after being told by Nissan on the last service that the oil leak was a rocker cover seal and them not getting one for me without the whole rocker cover, I decided to look for myself. No oil down the engine anywhere.

Found the rear seal on the transfer case was leaking. Filled it up and it took almost the whole prescribed amount of fluid so it was running pretty dry. Had to go to parent's place at Christmas so with the tailshaft off, 2WD only, it made the 700km trip there and back with hardly any oil used.

So closer inspection was warranted.
Found the rear engine mount had colapsed and this was probably putting extra load on the rear bearings of the transfer with the subsequent excessive wear leading to failure...good one Nissan for not finding this earlier.

Have all the parts and just waiting for the weather to clear up so I can get under and replace the front & rear engine mounts before having a mechanic help me with the bearings on the transfer pinion.

Missing the 4WD trips while waiting.

Well finally found what the noise was.
The sealing rubber of the sunroof was very dry and required lubricating where it sealed against the roof cavity.

I cleaned all the caked on dust from the rubber seal and then sprayed silicone spray all around. Then a few operations of the sunroof to make sure the lubricant was worked onto all the contacting parts of the rubber seal.

After a long trip on the weekend and a few days to-and-from work I can drive quietly without any annoying rattle or squeaking from the sunroof :o)

Fitted 225/70/16 Yokohama Geolandar AT/S tires today.
The road noise is very quiet and not audible at all.
Now I hear more of the wind noise from the roof basket.

A little rubbing from the front left on full right lock as the suspension is compressed but this is only the plastic wheel arch splash guard which can be pushed closer to the enginebay and the bashplate mounting clamps will hold it out of the way.

Check out the tires thread to see the pics.
I'll update with offroad and beach performance appraisals later once I give them a try-out.

Fitted these yesterday with Rich (basshead).
Not as easy as we first were led to believe from other posts so I guess they left out all the minor details and it sounded simple.
Anyway, we detailed all our steps as we went with photos so it will be a great DIY for anyone else to follow our lead.
Definitely a 2 person job for some of it and very worth the effort.