TR3-4A Plug shaft in crank. 1/2" long with a hex key slot.
This part is listed on the following pages of the website, where further information and background reading may be found.
Engine, Transmission, wheels/Tyres and Heating/Cooling »
CRANKSHAFTS AND CONNECTING RODS
Engine, Transmission, wheels/Tyres and Heating/Cooling »
4 CYLINDER TR2-4A