The changeover from the glued lens and 'permanent' lens was was not associated with pre or post facelift X5s. The change was made, if my memory serves me right which is very questionable was June of 2002. I have removed a 'permanent' lens. I would never do it again, took me forever to do without damaging the lens. Headlights have a date on them. There are many threads on headlight restoration. If you do a search you can confirm the changeover date.

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X5 4.6 2002 Black Sap, Black interior. 2013 X5M Melbourne Red, Bamboo interior
Dallas