8336 x 3 piece kit.  The special S.U. Flexible Spindle & 2x Brass End Joints on Carbs. The two bolt-up brass joint pieces  and the special flexible sprung rod between them that takes up engine movement from the bulkhead mounted first pedal actuated lever rod or outrigger.  Nice original S.U. branded pieces. Original Number C3597 \ C10033. AUC5079. AUC1924

NOTE: If the flexy spindle starts to 'unwind', you do not have a faulty 'spindle shaft', in reality you have a  jamming up carburettor linkage problem so check why the butterflies are siezing!