What can a failed rear flex disc mess up?
 

I had a flex disc failure, which wasn't epic, just slight vibrations one day. It got progressively worse over the next 2 days and I thought it was the center bearing, but it wasn't. I was able to change it 2 days into the bad vibration part. Everything went back together smoothly with no issues. I've been driving it around and car runs really smooth, no vibrations, not even slight. However, I did notice now there is a humming or droning noise from the rear. Best description I can think of is one of those small planes with a propeller on each wing that you can hear that's sort of far away. Other than that, there isn't any other symptoms.

because the drive shaft wasn't flat and flailing a bit, i imagine the center support and bearing and/or ujoint wore some. hope it's the support. if it's the joint, you need a driveshaft. only thing i can think of. good luck, chuck.

Anyway to test the u-joint? When I originally thought the problem was the center support I jacked up the car and checked it, but it was still intact and no torn rubber. Could it be the bearing in the center support? Not sure what a failing center support bearing would sound like. FYI Center support bearing and rubber was replaced 6/2018, not sure if that makes a difference or not in relation to the durability of the new parts withstanding streess from a worn part vs if the center support was a few years old.

If the center support bearing has enough wear to make noise but not enough to cause vibration, you can get the "growl" you mention. If the rear joint was moving around a fair bit, you can expect some stress on anything related to it. The U-joint should be smooth and free to move. If it seems stiff, or has any sort of "notchiness" to it, the bearings have failed. Stiff/notchy bearings WILL cause noise and vibration.

Found problem: excessive movement in all directions of rear passenger wheel. Appears to be just the axle part. No loud clicking or clunking of axle, but the outer part where the wheel bolts on to the hub.

sounds like wheel bearing to me. needs special tools. have an mb pro look at it to be sure. this is not a diy. good luck, chuck.

Good call! Hadn't even considered that. Especially since I just repacked both axles and replaced boots less than a year ago

Yup, wheel bearing replacement sucks, especially the wagons.

Wheel bearing was definitely shot. Ended up putting on an entire rear hub assembly from an E320. No more twin propeller noises. Brake dust shield was a little big, but the angle grinder brought it down to size in no time.