If I understand your question, you're asking about the thin plastic part that covers the plastic piece behind the chrome door opener. This can be pried off (careful, it breaks if you force it) to get access to the plastic piece behind. I forget if you have to take this off. Also, don't forget the door latch has a piece that has to come off. If you do get everything freed up, then lift up, don't pull it straight out, or else you'll break off the mounting plastic ears on the back of the door "skin".
Robert W. Roe
1984 300SD 172K mi