Well after checking best I can I’m 80% certain I have a standard diff, so I’ve drained and filled it with Castrol diff oil. I noticed drain plugs on front and rear diffs were really encrusted on the magnets with crud metal. I’m assuming my oil changes are the first the car has seen in 10 yrs Don’t know whether that’s an indication of 2 very worn out diffs? Though they aren’t whining or anything. I wonder how much of a difference there is in the oil for standard diffs and the the
e diff, how “special” can it really be?

From what I've gleaned, the ediff oil contains the same additive used in LSDs and that some brand diff oils of the correct viscosity contain the additive which previously had only been used in HD LSD oils. Using non-LSD oil in a LSD causes shuddering.

Hi Rapiscan, I've just completed my oil change on my rear diff and the posts here were very useful. Mine is a 2007 TDV8 and has the Ediff. The picture from GremeS is great but the only thing I can add is that you get a better idea of it being Ediff from the other side. You will see a black canister similar to a small spray can in size on the top of the diff. You can just make it out on GraemeS pic. You definitely have an Ediff if you see this.
I have heard lots of issues relating to Ediff with whining and squeaking. They seem to have more instances listed from Australia and they fixed the issue by using 75W-140 / 85W-140. The mechanics said that once they changed to this diff oil they never had any issues again from the vehicles that had been in.
I started hearing a squeak in hot weather and assumed it was brake squeak as it stopped when I applied brake pressure. But on inspecting my brakes the pads were greased up so shouldn't have been squeaking. As such I've changed my rear diff oil to this alternative diff oil and will see how things go. No more squeaks at present time.
Oh, no warning messages and no issues logged on my Icarsoft tool prior to or after oil change. So just precautionary measure on my part.