Notes: 100-0104631 FIFTH WHEEL 41.5X60X2.5 / RALLA is original CATERPILLAR product. 100-0104631 FIFTH WHEEL 41.5X60X2.5 / RALLA1 is commonly used in transmissions/axles/engines . if you have any questions please do not hesitate to contact us via Whatsapp +17275652849