FYI -

Earlier model J30 VLSD 93~94.5 came with 5 bolt output shafts. In order for the VLSD to work, you will need the half shafts / axles.

Later model J30 came with the same 6 bolt output shafts as s13 and s14s.

Into s13 chasis, you will need to change out the rear cover. Simply replace the rear diff cover with the stock s13 one and you are good to go.

Into s14 chasis, it is a direct bolt in.

The easiest diff swap for a s13 would be a stock LE (or ABS equiped s13), it would be a direct bolt in with nothing needed to be changed out.