1G3584 NUT.  Lock Nut for the gearbox input shaft on Leyland Lightweight tractors.
This nut holds the clutch spigot shaft/gearbox first motion shaft in place in combination with 1 x BTJ62 TAB.

See item number 5 in the illustration.

Fitted to tractors:

• BMC Mini
• Nuffield 4/25
• Leyland 154, 184, 235, 302
• Marshall 302