I eventualy got around to pulling the thing out yesterday, its a 3.64 slipper that needs an oil change for sure.
I never made sense of the tag (nor the main dealer) but Scott325se said you can divide one half of the number by the other or something and it would give the ratio

(it was easier to just turn the thing)
He also said that its a replacement diff from the original on the car, which would explain the strange tag.
If someone wants to make sense of some more numbers you could explain these to me
Cheers.
There is NO nucleus.