I'd check the bulbs, and if they're not burned out if use a test light to see if they're getting juice. I didn't think they were on the same fuse though so another culprit could be the light switch

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1982 300D Turbodiesel, daily driver. Mods so far: Fram 8038 paper filter, 4 brake light mod, Gen II w126 (front) rotors/calipers, boost turned up to 12lbs, non-egr manifolds, water/methanol injection, 4-speed manual
1980 300SD Turbodiesel, project car, nearly ready to hit the street

1974 240D, New paint