If your outer boot is torn (which is common on X5) you can replace using this kit as long as the tear is fairly new. The amount of work required to replace the boot is more than replacing the axle with a rebuilt. Chances are the inner boot is pretty close to wearing out as well. GKN makes the original axles, you can also get a new replacement through FCP for new full axle.

Bought this to repair the boot that was on the front drive axel, compared the price is less the OEM. I have purchased OEM in the past, also comparing what you receive you get all you need to replace the boot. Including the axel nut. the only thing different is the boot itself the OEM is a little heavier rubber compound but is also most double the cost. How long will it last mm idk comparing to original.