As I read more information of this differential "swap" I noticed a very critical error in my plan, Zeta already had the mentioned differential aka R200. The only difference was that Zeta has the "long nose" -version and no LSD.
As Zeta has this part as an OEM part, swapping to this differential does not give any real advantage and so it went back to my friend as went the rest of the parts that came from his Z32.
I highly urge anyone that is interested in changing their differential, to read this thread in Hybridz: Differentials 101. It will make everything much easier.
I'm planning to add a Limited Slip -lock to my differential with an OBX unit. One can read all about it in these threads/links: OBX Differential Inspection and Installation, How to Rebuild your OBX Differential and OBX vs Quaife (with pixors).
This unit is made for the Nissan 300zx and 240sx and it should be a direct swap. Just got to make sure that the unit is meant for the non-lsd version of the 300zx or 240sx, because factory lock is not interchangeable with the normal differential. At least according to the Hybridz forums!
There also has been some problems with OBX units but with proper installation and tuning it should be "just what the doctor ordered"!