[Jeremy R.]

The 1999-2001 and 2006+ rear bushings are the ones to use. They're solid rubber and don't have the voids you can see in your picture. I used the solid bushings in all six positions on my 2000 and 2001 9-5s. Even at 200,000 miles, the 2000's rear bushings were pretty decent, but the center ones were pretty bad. The rear bushings on the 2002-2005 models don't even seem to last 100,000 miles. The front and center bushings seem to be interchangeable on all years, and if the front and middle bushings are the same part number as Doug says, then you should be good to use whatever bushings you want in all 6 positions. 2002-2005 were the odd years with the plastic-sleeved center bushings and rear bushings with voids. There's a service document from Saab out there somewhere that says that they did it so that the subframe would shear off in a crash. Why they thought that needed to happen is beyond me, but apparently they came to their senses and went back to the 1999-2001 setup in 2006.

 

[Jeremy R.]

I haven't noticed any more vibrations after using the solid bushings in all six locations in either of my 9-5s. I think on 2002+ models, you have to use the original bushings in the center positions, though.