I wanted to do that too. It takes an 82 Maxima with the electronic over drive. I know that you have to change drive shafts as well. Do a search on this site, I think you will fi.nd the info you need.

I've done this swap in my Nissan Cedric 1978 year model.

You'll need:

The 4 speed flexplate,

An overdrive rocker switch to lock out O/D

A modified crossmember.

A modified tailshaft (shorter and different spline than the original)

Some slight transmission tunnel adjustments (read, make larger at some points where the trans touches the tunnel)

These are things that i had to consider and do to make things work, you may have some of these issues with your S30 cars...dunno, never owned one myself.

A worthy modification IMO. Good luck mate, Cheers.

PS My 4 speed auto was from an R30 Skyline with an L24...it was a hydraulic box. Some later ones are electronic. That may need more work to set up the electrics but I don't know about this, as I said, mines hydraulic.