Not center diff its front diff as i specified. But to my understanding he ran the wrong mix in it. The gear set alone is worth 500 with no front or rear diffs I'm including everything. Yes it should fit a 04-06 with out any mods and should fit a WRX with some minor changes (clutch setup)
I'm open to offers
And yes I'm building a 818, I decided to rebuild my STi-RA gearbox and use it vs using this one.