its extremely easy,, behind the markers (under the hood), there is a large tab.
push this protruding tab and they will pop right out!
i don't know any part no.'s though, i bought mine on e-bay. they look great. some people think they are not as good as stock though.
good luck,
adam

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87 300E
BLACK GOLD WITH CREAM INTERIOR, SPOILER, AIRDAM
CLEAR MARKERS

87 420SEL
BRONZE WITH CREAM INTERIOR