Diff wise: JZX90 & JZX100 will swap with each other only (as long as 6 bolt CV hubs on diff), not with supra/soarer tho etc as recently found out totally different.
Brakes: yes JZA80 rotors and calipers will bolt straight onto JZX90/100 series. Have bolted to my JZX90 before & my friends JZX100 is currently running at the moment.
Have both available if required too...($650 exchange torsen diff/$600 4pots & rotors)
Hope this helps, have fun
