Hi oldduke. Just because the part is NLA from Volvo and ipd is no longer able to source an aftermarket generic that would fit, you know as well as I do there is of course such a thing as a muffler bearing. They were available as a dealer option to give a throatier exhaust sound. The only reason you don't hear about them more often here on the brickboard is they rarely fail, and like you said, they were rather expensive for what they are. I think there's an article on them somewhere in the FAQ.

Here's an excellent video on how to diagnose a faulty one, locate and change them
How to change a muffler bearing (Youtube video)

He also talks about changing blinker fluid and as well switching from winter to summer air in your tires. He uses a noname blinker fluid, but I've always found the Genuine Volvo fluid has a longer life.

I'm telling you, and I'm sure you'll agree, the young people of today simply aren't well versed in the basics of good old fashioned automechanics. People just don't seem to care any more about properly maintaining their cars for a longer life. Everything is so disposable. Can't even be bothered to use a bucket of steam to properly clean under the hood.

(okay, this should have been posted on the first day of this month).
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now