Shouldn't be too bad. You shouldn't have to remove the spring. Either compress it or pull the integral link out and have push down on the knuckle to make enough room to get the seat out.

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2004 X5 3.0 6 Speed MT
Build Date - 09/03
156K Alpine White / Black
Premium & Cold Weather Packs, Nav,
Tons of lighting mods, 4.8is Exhaust, Headers, Eibach Springs, OEM 87's, Custom DME Tune, OEM Hitch.

2005 X3 3.0i - 100K - Blue water Metallic / Black

2005 X5 3.0i - 140K - Alpine White / Hellbeige 2