A Torsen is NOT a Limited Slip. But we're splitting hairs. I actually think the Torsen is a better device for a street car since it goes from 1% to 99% torque on one wheel. Definitely NOT good if one wheel is off the ground.
A true LSD has clutches and gives a certain percentage of lockup: 20, 30, 40% or so, depending on design and clutch material condition. The geared design does not give you lockup under braking, which is usually a good thing and intended/needed for track usage. The only ones of this type are the factory ZF and those are all expensive unobtanium or completely worn out. They are pretty rare today.
Peloquin and Quaife are both still available to fit a swing trans as far as I know. Weddle has one too, but it might just be a re-branded Quaife or Peloquin.
@JMM (Michael) posted:
If you got it from Rancho it's probably a Peloquin torsen style lsd. It is essentially a Quiafe in operation and design but was made specifically for the VW transmission cases. A 3.88 r&p is the end of the range it will fit, though, so no 3.44. I have this exact one in my type 1 transmission. I figured that with a worked Subie in my coupe, and often wet roads, it would be prudent to have one...also, hole shots.
Many will argue that a torsen gear type differential isn't a true lsd and that title can only be assigned to a clutch type. There are a few ZF clutch types out there for a type 1, and they are quite sought after. If you are going to go Subie transmission you'll be able to get a clutch type (OS Giken), a torsen (Quaife, or Wavetrac which I think has adjustable preload so it acts a little more like a clutch type), or just a stock Subie torsen lsd.
I mentioned the max 3.88 and non-fitment of the 3.44 above. I have heard various folks say that the 3.44 could fit with some machine work. I'm not sure of this.
I also believe that Paul Guard of Guard Transmissions makes a swing Torsen as well. I believe it's $2200 or so.