Noticed a brown-gray oil on garage floor near rear wheel. Then noticed clunking sound in rear suspension while driving. The under hood air compressor that inflates the air struts began working overtime and had to be disconnected at the quick-connect to avoid burning it out. Called Buick dealer and they wanted $700 for these air struts. This is just the (2) struts --- no labor! I'd be surprised if this repair was not more than $1,000 parts and labor at the dealership. Went online and found OEM replacements at Arnott Inc.for $200 for a pair. They are air struts with the electrical fittings for computer/leveling sensor control. Other vendors offer non air struts for about the same price, but you lose the automatic leveling feature with the car and you must install a work-around to permanently eliminate the check engine light when the electrical connection is no longer made with the struts. You basically have to fool the computer into thinking the air struts are still there and working properly. Not with these babies, though. Here's the URL for Arnott Inc.

http://www.arnottindustries.com/part_BUICK_Air_Suspension_Parts_yid10_pid85.html

They look like a good value. We'll see how they perform over the long haul. I think they'll be fine. Manufacturer suggests they will last 80,000 or so miles. About the same as the original equipment on my car. I also like saving a cool $500 anytime I can!