Dropped Ft Drive Shaft to replace CPS, Now vibration in 2WD at 45 MPH

Yesterday I dropped the front drive shaft to replace the CPS on my daughter's '99 XJ. (There was a previous thread on this by my neighbor Mike.) Thought I had reassembled the front drive shaft at the front universal joint exactly as came out, but now at or above 45 MPH there is a really bad vibration through the truck. It is NOT in 4WD, it's in 2H. Engine is running great. Not missing through the rpm range. At 50 mph I can put it in neutral and the XJ still vibrates the same. Difficult to tell where the vibration is coming from...the whole truck is shaking. It was not vibrating prior to the CPS replacement. Below 40 MPH it runs well. No missing wheel balance weights, but it feels like a very out-of-balance wheel. Gotta believe it is not related to the CPS replacement. No clunking noises like a bad universal joint. Guess I'll have the wheels balanced tomorrow just to start eliminating stuff. Rear drive shaft has not been touched, so I can't believe it is out of balance. Any other ideas??

Take the front shaft off at both ends and rotate it 180* and remount it.

Also, did you use new straps at the axle end, the old straps may be too stretched to hold it tightly.

U-joints look good?

Slip joint?

Center ball joint?

There is not to many things that it could be if all you did was remove the shaft.

I assume you did not actually seperate the slip yoke on the driveshaft to make it out of sync and unbalanced? Just make sure the yokes are aligned. Beyond that there is only one other way it would slide on, 180 degees spun the other way. If the yokes are not lined up it will vibrate, but also could vibrate if the weights were 180 degrees off. But if you did not seperate the driveshaft I doubt that is your problem.

Nope, I didn't separate the slip yoke from the drive shaft, but it is very possible I got it 180 degrees off. Let me try that. Will also replace the straps.

The u-joint was 180 degrees off and not centered in the yoke. That fixed it. Thanks for the tips!