If it is an esay locker and it says 9" on the box, then yes it will cause it is the SAME EXCAIT THING as the 8". However, I would stay away from the EZ lockers. They will work fine and danddy in a 9" as the 9" has two pinion shafts (preventing side to side and up and down movement of the clutches). However, the 8" only has one, so that means that the locker's clutchs can move side to side (or up and down) causing them to not properly mess with the side gears and that will cause you to not get any power to the wheels. They do work, but because of this poor design, I don't trust them. How do I know this? I had one that did the very same thing. I spent $283 and all I gained was and extra dissassembling of my diff and drive back to the diff shop to have it removed (yes, it was PROFESSIONALLY installed). Posi isn't something you need, it is something you want. So I suggest that you save up the extra $$$ and get LSD unit. Trust me.