Might be a fuse? Can't remember if those are separate but the rear tail lights are separate. I thought my right tail light was the bulb holder but then i found the 3rd fuse box on side of driver side instrument panel. Open driver door and you'll see it. Is there a right reverse light fuse in there?

__________________
What Would Rudolph Do?
1975 300D, 1975 240D, 1985 300SD, 1997 300D, 2005 E320 , 2006 Toyota Prius