The Cusco front diff is LSD 1C7 V15 and runs $1800. Looks like the assy with case is 41301-52340 - $5,500. Maybe someone can look up just the diff part.
On a GRY forum they said you have to split the transmission case to get to the diff.
Supposedly you can buy a whole used transmission and just swap that.
Coming from drifting and the magnitude of ways to mess up parts on order / casings, in the future to anyone who reads this, be sure to always order what your car needs.
If your car was a base model open diff, ensure the aftermarket diff is designed for the open diff casing.
Also, installing a diff is not that difficult into a casing, but shimming and breaking the diff in properly without issue from local police / authorities will be your biggest challenge as most require you to do slow alternating figure 8’s for 30 minutes.
Added bonus, aftermarket clutch type differentials like KAAZ and Cusco will feel super clunky. Your car will “lurch” forward and you’ll feel the entire chassis rumble. 100% entirely normal. Keep this in mind that it will be rough on your chassis, drivetrain, tires, and overall wear and tear lifecycle.
I had a 2 way before for one of my S14 chassis builds and it’s really aggressive for the street. You can always remove some clutches when having the differential pressed in property and whatnot, but a 1-way / 1.5 way would be better for most people.
I think depending where I end up with this chassis, I may have a rear aftermarket differential. Kind of just waiting / paying the car off for a few years til I see parts I want.