There are different types of quaife lsds for each model. If you happen to have the sport model 370z with the vlsd and you buy the quaife made for the sport model then you will just need to cut the longer stub axle down to accommodate the the quaife lsd.
If you happen to have the base model 370z with the open diff then you will not need to do anything but swap the two short stub axles you have no modification required.
Hope that clears things up.
For me I was a dingus and had an open diff and bought a fully built quaife diff for a sport model and had a bit of confusion with the setups since I assumed it was all the same.
Hope this helps !
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