Notes: 226-4378/GEUG43785 EPIC.PLANETARY GEAR Z31 M2.9295 L50 is original CATERPILLAR product. 226-4378/GEUG43785 EPIC.PLANETARY GEAR Z31 M2.9295 L501 is commonly used in transmissions/axles/engines . if you have any questions please do not hesitate to contact us via Whatsapp +17275652849