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After: With the Super-Flex U-joint installed, the two yokes are significantly farther apart at full droop. Because the Super-Flex has offset trunnions, there can be driveshaft vibration. Generally, the amount of vibration varies by vehicle and is relative to the angle of the driveline and the rpm of the shaft. Naturally, you wouldn't want to install a Super-Flex on the front driveshaft of a vehicle that doesn't have lockout hubs due to the vibration. With the four-wheel-drive system engaged, our Chevy exhibited medium driveline vibration up through 30 mph and light driveline vibration through 45 mph. Bottom line: The Super-Flex is designed to solve binding issues, but it's important to recognize its inherent limitations and abide by the manufacturer's recommendations.