I did the door swap, its easy!! hinges are simple to pull apart, the doors are surprisingly heavy!
DO DISCONNECT THE BATTERY, then drain any residual capacitor charge by touching the two wire leads together (NOT while either one is still connected to the battery!!!!!!!)
I removed the door panel, and disconnected the door swing stopper first (forget the technical name for it!!) then the harness.
good luck!!!

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2003 X5 3.0i (02/2003) sport package, Sapphire black metallic / Black Dakota Sport seats. compass mirror retrofit, trailer hitch retrofit, Prodigy P2 trailer brake controller installed, PDC retrofit, Lumbar support retrofit. heated rear seats retrofitted. Running boards retrofitted and subwoofer install in progress. 4.8is Brakes installed front and back. Bluetooth TCU installed, Rear Fog lights installed. Retrofitted reclining rear seat backs.