So here's the history that led to me posting this information. It wasn't easily found on the forum so I ended up spending the time and $$ to find it out. Hopefully I post enough info for your projects.

I have a S5 vert. that I'm converting into a turbo car. My other car is a S5 turbo that I bought a Torsen differential for and it was already in the housing. I just had to bold it in. This left me with a blown viscous TII diff.

When the vert project started, I elected to install a torsen since I had one in the garage. I got the carrier installed and tried to plug in the stub axles from the viscous type.... failure. The viscous type had a long stub which was too long (it locked both sides of the torsen) and a short stub which was too short (it didn't lock into place).

As a result, I had to locate another diff to install in my car. A S4 clutch type came my way and I pulled the stubs out to compare. They are the perfect size for the torsen.

The pic attached has a S4 stub on the left and a S5 stub on the right.

So here's the conclusion.

S4 TII guys can swap a 3rd gen torsen into their housing and use their existing stubs.

S5 TII guys have to locate the stubs from a S4 TII or cut the long S5 stub to match the short S5 stub and just let both stubs float in the diff... with the hope that they won't pop out in a corner.

I haven't been able to find a source for these stubs other than Mazda.