The Torsen rear LSD was a factory/dealer option for the first Generation Rav4 in fact, in scrapyards around North America sit several, but tracking them down, next to impossible.  I've completed my swap by way of disassmbling a Caldina GT-T rear differential, and moving the internal components into the Rav4 rear differential, the JDM Celica GT four from 1994-1999's rear differential outer casing is different, but the internal components are identical to the Caldina GT-T's.  You will have to purchase two Quantity: 2 (two) SHAFT SUB ASSEMBLY DIFFERENTIAL SIDE GEAR Toyota Part Number: 41309-42011 from your local Toyota Dealer, in addition to acquiring the rear diff from a Celica GTfour, or Caldina.  There may be other compatible rear diff's out there, but for now I am not aware of any.

To Remove the Sub Shafts from the Rav4 rear differential, you need to first open the differential casing, and remove the clips from the end of the sub shaft assemblies.

The designs of the retention clip are different between the OPEN and LSD Sub Shaft's and do not match the Celica or Caldina dimensions although they look damn close.

To remove the LSD sub shafts simply pop them out using a long handled pry bar on both sides to evenly distribute the force, or do what I did, attach chains to the studs and yank it hard with something heavy attached (big C clamp works)