Notes: 26366-050002 NUT, M5 is original YANMAR product. 26366-050002 NUT, M55 is commonly used in transmissions/axles/engines 100AEDEGYT5B, 5500E-5BG, 5500E-5EBG1, 6600TE5EBG1, 6600TE5EBN1, . if you have any questions please do not hesitate to contact us via Whatsapp +17275652849