Hi ehoe,
Can you tell me a bit about the history of these shocks ?. Like:did you buy it new ?. How long have used it ?. What E34 model was it installed and roughly how many kms/years was it used. Do you have the original receipts ?.
The main problem with used things is that if the history is not exactly known, it hard to tell how much "life" is left in the part for buyers. Someone did ask if they were serviable. If not designed for services, so cannot be properly "re-conded" or re-manufactured as the Americans like to call it.
Of course, some shops can do proper reconditioning by taking it apart, but then its risky becuase valving ratio needs to be calibrated properly. I only trust German companies to do this. A German friend knows one that re-valve bike shocks. Rather expensive but is the only way for people who wanted to tune their shocks to their own specifications.