Re: strut mount replacement: mandatory?

[todd@qualmedoregon.com]

> > Yep, bearings are what I'm referring to as strut mounts.
> > That's the price for the front, and since the front gets
> > more stress (usually) because of braking, I was going to
> > replace those anyway.  The ones in back cost upwards of
> > $25 a side, though, so I wasn't sure if I was throwing
> > money away if I got those just because I was replacing
> > the struts.
> 
> You can use the front bearings in the rear instead of the blue UrQ
> bearings in the rear which is what the dealer says you need.  
> Like $95 for the blue urq bearings and $12 for the black 4kq 
> fronts.
> 
> Mark

Now this I find interesting.  What is the difference between
the two that make the Quattro rear bearings so much more
expensive?  Is it really safe to use the front ones in back?
For that matter, are the ones already on my car more like
the blue UrQ ones or the black front ones?