Gellie - not meant as a smart assed answer at all - sorry you took it that way. I just wondered the same thing on mine a few weeks ago and lo and behold when I opened the trunk, the bulb/socket just pulls right out. I can't imagine your '89 is any different than mine.

__________________
Len
'59 220S Cabriolet-SOLD and living happily in Malta
'83 240D 351,500 miles original owner-SOLD
'88 560SL 41,000 miles - totaled and parted out
https://sites.google.com/site/mercedesstuff/home
'99 E300 turbo 227,500 miles
'03 SLK320 40,000 miles - gave to my daughter
'14 Smart electric coupe 28,500 miles
'14 Smart electric cabriolet 28,500 miles
'15 Smart electric coupe 28,000 miles