The S12 didn't come with an LSD. Do you know what type you have? Is it the S13 vLSD conversion or do you have a proper KAAZ/Nismo setup?
I'm guessing that it's the former and if that's the case then you'd need to swap both the diff housing and the O/S drive shaft + Inner shaft to transplant it. AFAIK the rear subframe is the same for the MK1 and MK2.
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