Notes: 51335937 STUD ACCIAIO CL. 10.9 UNI EN 20898 R18X2 is original NEW-HOLLAND product. 51335937 STUD ACCIAIO CL. 10.9 UNI EN 20898 R18X21 is commonly used in transmissions/axles/engines . if you have any questions please do not hesitate to contact us via Whatsapp +17275652849