Heard a slight hum this morning, only lasted a second and went away. Sounded more like an old fashioned train whistle.

It got me thinking about the wheel bearings I just repacked a few months ago and drive shafts and assorted attached parts.

Pulled the wheels, yes I did have to slightly snug one spindle nut..don't think that was the issue ( i hope it was).

I have 258000miles and I have never changed a 'U' or Center bearing or that Rubber Damper/Coupler/whatever it is that joins the M47 trani to the driveshaft.

I rolled under the car and everything is still tight.
Questions.
1. Has anyone replaced that Rubber Coupler thing that joins the Trani to the Shaft? Mine has some slight cracking in it but not beat up by any means.

2. My center bearing is still quiet ( except for what I might have heard this morning) with some lifting and pushing, would there be play in the bearing to let me know to replace it or do I wait for noise?

3. What the heck is with Volvo 'U' joints?!?! 200+K miles and they are still tight. I've never had that on any car I have ever owned. Amazing.
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'75 Jeep CJ5 345Hp ChevyPwrd, two motorcycles, '85 Pickup: The '89 Volvo is the newest vehicle I own. it wasn't Volvos safety , it was Longevity that sold me