Be careful with that. They sometimes look similar, but don't fit. I bought on ebay a set of rails marked as "for E46", but they didn't fit our X3. It seems there were some E46 (the first ones maybe) that had the same rails as the E36. On the other hand, I have a friend with a 3 E46 and a 5, and the rails are the same, but the 5 is larger and the rails don't fit each other.

To be safe, buy something that really says X3. They can be bought for around €100 (or $$$ equivalent), so it's not worth to safe a dozen dollars and get a non fitting rail.

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