'99 E300 "License plate lamp replacement ?
 

Do you access the bulb by taking off external plate or by going thru inside which involves taking off entire inner trunk cover ? i took the external plate off but couldn't get bulb cover out - i was afraid to pull on it too hard - seems i remember reading here that this isn't an easy job - but i couldn't find out how thru searching - any ideas ?

It is not too bad of a job. I took off the backplate and the trunk liner. The plastic retainers come off pretty easy. You need to work the liner around the trunk hinges a little to lower the panel. I was able to reach in there and release the plastic clips without removing the panel totaly. Thats the only access you will need and the lamp housing pops out at the removed rear trimpiece. Jim

Do yourself a favor and replace both at the same time or you will be pulling down that liner again within a year (ask me how I know!).