I just finished replacing my rear driveshaft u joints. I drove it and now I have bad vibration. I marked everything and thought I put it back together the same way but I must have screwed up. The question now is how do I fix it? I am thinking the drive flanges are out of phase but what does that mean. How do I tell phase by looking at it. If it is out of phase, do I have to press a u joint back out to fix it or can I slip the yoke off and just rotate by 90 degrees? Advice?