I'll have to look at it again, but I didn't feel any resistance in any movement of the u joint when I was checking it. What do you mean by "notch"?

70 is about 103 ft/sec out tires are 5.7' circumference so 103/5.7=18.07 Hz at 70. 18*4.1=73.8 Hz aka 73.8*60=4428 RPM. That's definitely fast enough to be a problem with a small weight off balance.

I'm a little concerned about the possibility of under load causing an issue but that would be very similar to my theory of my under braking causing vibration.

Do you get UFO noises when backing up?

No UFO noises. That's why I didn't think it would be a wheel bearing. All the reading I've done on it the common denominator with a wheel bearing is the UFO noise. I'm not getting a crunchy noises from my CV joints either so :dunno:

Driveshaft shake should be about 74hz on the vibration app but I don't know if it goes that high.

Use this app or similar to get an audio reading:.

https://apps.apple.com/us/app/fft/id298840058

As you have it disconnected, move the u-joint through is movement. There was the slightest notch when it got to one point. I MEAN SLIGHT! You could barely feel it but you will notice it.

Ya, only goes to 50hz.

I'll try this other. Thanks!

I had it apart when I replaced the CSB. I moved it though all motions, full range. It felt smooth.

UFO sound comes from differential. Mostly noticable in reverse.

My bearing was silent for years but the suspect in my wobble/shimmy. I will know soon just swapped alternator and ready to test drive.

That's good to know. Definitely no UFO noises.

https://uploads.tapatalk-cdn.com/202...ee3dc09197.jpg

Here is an example from the FFT program. You can drag out a cursor to figure out exactly where the Spike is. You can also change the ex and Y axis so you can zoom in on a particular frequency range.