Also, most auto parts stores have catalogs that will lost the proper bulb. The only problem I've run into is with my CLK - all the books list the dual-filament bulb for the brake lights, but it's actually a single-filament. You might just want to remove the bad bulb and take it to a parts store to get the replacement. And FYI, go ahead and replace both of them - the other will fail shortly!
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