I own a 2007 Volvo V50. There was some suspension noise and I knew I needed to replace the control arms (the ball joints and bushings are integral to the control arm). I have an account on All Data DIY, which is just an online service manual with lots of great info. I bought OEM parts online from a volvo parts seller, and drove to my mother's house to have access to a garage and my tools. After some difficulty in the heat and rain last week, I removed the old arms and began to install the new ones. With the passenger side installed, I begin the driver side only to realize that I was sent two passenger side control arms. Now what?! I checked the packing list and the parts themselves when the arrived, but I didnt actually take them out and place them side by side to make sure I had a matching pair. The other "passenger" side was labeled with the driver side part number so I concluded that this was not my error. The online seller sent me a return label to ship the wrong part for a refund, but the correct part wouldn't arrive for 2 days since I called them after normal working hours. I decided I didn't want to wait, so the next morning I went to my local Volvo dealer who said they had it in stock. When I arrived, the guy pulled the part and put it on the counter, and I scratched my head for a minute since I swore it looked like the passenger side. He insisted it was the driver side since the part number matched his database, but I then asked him to pull the passenger side part. Lo and behold, they were the same! Now I realized that it was a good thing I was able to lay my hands on the part because there was a good chance the "correct" one being shipped to me was also wrong. There must be hundreds or thousands of them mislabeled for me to encounter this problem on the first 2 randomly selected parts from different areas of the country. So I drive back to my mother's (using her car that I stole for the night) and put on the correct part. This error wound up costing me about $100 more than it should have, and I will contact Volvo corporate to see if I can get some credit or something. Since both parts would have fit the passenger side, it is fortunate that i installed the one with the correct part number, otherwise I would have to try returning a correctly labeled part.
tl;dr, I bought driver and passenger side parts from an online seller. Received two passenger side parts, one with a driver side part number. Encountered the same problem at a local parts dealer and realized this is some factory screw up. Cost me about $100 and a day without my car.