I do not fully understand what you are sking for but most people use the Supra diff from a non turbo supra (3.9). If you are taling about the Skyline gearbox then have a search on the recent threads. I thinnk with this setup you can use the std front diff.

I know with an after market box I need 3.9 drop gears in the MT75 to work.

I hope this helps.

MK motorsport make the supra diff fitting kit and Bara motorsport can rebuild the diffs.

I hope this helps.