Genuine Mazda Counter Gear Shaft Locking Nut (Clutch Hub).
Used in all 6 speed gearboxes for the Mazda MX5 MK3, 3.5, 3.75 and RX8.
Common failure point on early pre 2009 gearboxes is the 3rd/4th gear selector. Advisable to replace locking nuts when disassembling shafts to replace selector fork.
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