I have a 03 x5. 4.4 with 125k miles. It's a love hate relationship. I love it when I'm not sinking money into it. So, about 8 months ago. Pulled away from stop light and big clunk and engine winds up and sounds like metal on metal grinding. No power what so ever and car moves freely even when in park. I'm thinking broken drive train. Took to my bmw mechanic. He said broken axle. Sounded right, well 1400 bucks later I leave and runs fine. Now 8 months later same exact thing happened. So, Now I'm thinking is it the other axle. I can't really which axle is broken since the noise is so loud could be from either side and just doesn't sound like I should be running car in gear. Point being I'm looking up axles on e-bay and such and they are running under 100 dollars. And I would think that I would have some kind of warning that I might be breaking a axle. I have kept the boots up fairly timely. Not perfect but not neglect either. Any words of wisdom? Is it a fairly easy fix I can do on my own. I have changed brakes, water pump, radiator, and such before. 1400 just seems way to high? Or could it have been something else? Thanks.