UPDATE for the archives
Just wanted to state the correct procedurefor removing the shifter on a pre-1996 W140. There are no bolts to loosen and it could not be easier to remove.
AllData had it right.....
Simply take a large rubber mallet and give the shifter a good downward whack while at the same time turning it clockwise. It will loosen and pop right out.
You can then buy the $15 adapter from Performance Products and relace that old worn out shifter with a modern looking version from any newer model Mercedes.