The original (chrome/rubber bushing) antenna mount on my '83 380SL came loose while driving one day and fell off...unfortunately the replacement part from the dealer is only a rubber bushing variant.

Installing it was rather simple although I did have to remove the antenna (but only partially) enough to use a pair of channel lock pliers to properly seat the new seal.

From the driver's side boot/trunk, you'll remove the plastic grommets (just pop out) to expose the antenna.

Total time: less than :15 minutes
Difficulty: very easy