Interpump RS99 Gearbox – 3/4" Shaft, 2.4:1 Ratio for SAE J609A FlangeThe Interpump RS99 Gearbox is engineered for compact engine driven pressure washer setups, enabling seamless connection between engines with a SAE J609A flange and Interpump Series 44, 49, 50, 53, 58, 60, 63, and MF1 pumps. This model features a 3 4" (19. 05mm) hollow shaft and a 2. 4: 1 gear reduction, delivering reliable torque and performance at a reduced pump speed. With a power capacity of up to 6. 5 Hp (4. 8 kW) and a max input speed of 3450