Here we have for sale a CTC stainless steel rear linkage bolt Yamaha part number 90101-12597. 
This fits all YamahaTY250 & 350 Mono bikes all years and models.
This Linkage Bolt is no longer available from Yamaha, so we have had them re-manufactured to OE Specification using 316 Stainless Steel, so they will never go rusty again.
This is shown and replaces part numbers 49,50 & 51 on the swinging arm parts diagram.
We also have complete linkage Bush, Bearing, Seal and bolt kits available in our shop.