OEM JZA80 Supra 6 speed V160 / V161 output shaft nut.
This is the nut that attaches the tailshaft to the back of the gearbox which is a very uncommon thread pitch of M11.
Note: This doesn't come in original packaging as Toyota doesn't sell them individually and I buy them in bulk to make sets. This listing is for a single nut and a total of four are required.
If you are looking for the washers that go with this you can find them HERE