The squeaky noise is from the REAR balljoint going bad. At 170K, you bet money it is gone.
I don't have DIYs for E53 but I wrote FRONT and REAR suspension oevrhaul for the E39, you can use it as a reference:
DIY: 1998 BMW 528i COMPLETE FRONT SUSPENSION OVERHAUL - Bimmerfest - BMW Forums
DIY: 1998 BMW 528i Complete REAR Suspension Overhaul - Bimmerfest - BMW Forums
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1998 E39 528i 5sp MT
2006 E53 X5 3.0 6sp MT
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