They aren't externally adjustable like koni's, but they can be revalved by taking them apart. There are some very knowledgeable people who say bilsteins are better than koni's once the valving is correct:

http://farnorthracing.com/autocross_secrets.html

Since I already have the bilsteins for the front, I figure I may as well go with them in the rear too. The rabbit bilsteins are the only good insert i know of that will fit, the rabbit koni will not (too wide).

Are the Bilsteins adjustable? or fixed

So I'm awaiting shipment of some used bilstein VW rabbit sport strut inserts that I scored for $70. I plan to use these in my 1200 coupe with some 82-92 camaro bilstein rear shocks, part number ak1050. The camaro rear shocks have linear valving used in short track racing. The rabbit inserts also have linear valving.
According to the bilstein rep I talked to today, the valving for this setup is as follows (measured in pounds of force at 10 inches a second):

rabbit inserts: 256 rebound/72 compression

AK1050 camaro short track rear shocks: 213 rebound/118 compression

The bilstein tech I spoke with said the rabbit inserts would have good valving, but that I may not like the camaro rear shocks on my little car. But he actually reccomended valving in the 200/75 range. He told me to fax him the measurements of my rear shocks and the leaf spring rates, which I don't know, and he would liook at it further. I'm sort of stuck here because I don't know the rear spring rates. I'm guessing about 100 lb/inch?

Hopefully I can find soemthing that will fit and won't require a revalve right away.

Thoughts?