You know. I honestly have no idea what the warranty is nor do I even care. I bought it solely because it performs better and has better torque biasing.
I picked mine up for under $600 shipped. It also had the bearings pressed on and a new speedo gear.

(I.E. straight drop in and didn't need any $$$ shims)
Like I have stated countless times before.
I choose performance and Torsen has a great track record anyway. (for instance several race teams switching to it over the Quaife

)
It is really as simple as that.