Sorry for the late reply, been off the internet for a while with the unemployment...
Cedric, I went to LSX in 2007 when I thought I had a LSD in the rear of the Sani. I was at that time told that the oil spec is better on the LSX and would not hurt my non LSD front diff.
I ran two flushes at 1000km intervals through both the front and rear diff to clean them. The oil came out perfect and at stripping down for the SFA found the diffs both in excellent condition. The teeth on the crown wheel still has its machine marks mating surfaces. I at that time also found that the rear C200 was not a LSD unit, so the oil was overkill all this time.
The oil I used in 2007 to flush the diffs, I have now dumped into the front diff to do a clean out and flush and keep it lubricated while the project is on hold and I eventually get it back to 4x4 and linked to the transfer case. I have been running the manual hubs in locked position for more than a month to just keep the oil splashing around inside the housing.
The rear H260 seems to be a LSD unit, and I have found a few references to these LSD units being super tight. Even found an upgrade, where for $7.95Aus, you can add a 0.7 shim to the LSD plate pack to make the diff an "almost locked" device.
http://www.ebay.co.uk/itm/Nissan-Patrol ... 463149d3b2
Anyways, so the LSX oil will be going into the rear end. The diff still needs to be stripped and the input seal replaced, and I hope to find that the diff has not been welded, as I have never come across a diff that I can not, for love or money, turn the wheels in opposite direction to each other.
But our mechanic here tells me that he has come across other LSD's that have acted the same way, so I am hoping he is right.
I did come across someone that has broken one of these H260 diffs though, but I feel confident that my 2,7TD, even through a doubler box, will not be putting 600WHP, into it.