That's probably the most valuable component of the whole part-out.
Once I sell any part, I'm committing to parting the entire thing & trans.
It was a $1500 part, and required a good stock diff to transplant the planet gears. Unclear if your replacing an exploded diff or not, but I'd sell it complete - $1k
If you have never driven a FWD vehicle with POSI, but it is a startling mod. Makes the car torque steer quite hard compared to the stock open diff. Also gives you amazing traction coming out of corners, or making a right turn into traffic - you can basically accelerate as if you were in a straight line when cornering. Which also leads to added stress to the half shafts. My car was around 450WHP and broke a fair share of them.
Also; if you floor it on a road that has a crown to it; assuming your car makes a lot of power and breaks tires free at speed; having POSI will make the entire car drift toward the curb while spinning, as opposed to the open diff which goes more straight, and limits traction a bit. (i.e. you basically have to /DRIVE/ the car)
The diff makes a stupid big difference; I've never experienced anything quite like it.
Torsen Differential, How it works ? - YouTube