Trying to figure out what series u-joint you have? We have the tool for you - and it’s free! All you have to do is head to the Gear Squad section of 4WheelParts.com, download this ruler, and print it out to determine what series yoke you're working with.   Just place the notch against the tang on your yoke and see where the other tang lands. The other side of the ruler has a tab sticking up. This is for your actual u-joint.