There is a bezel that is black and surrounds the lock cylinder.  If your
lock has a single poke hole, then the bezel is threaded.  Once the wire
depresses the retainer, the bezel can unscrew.

If you have the kind with two poke holes, one poke hole will release the
bezel (not threaded) and the other will release the ignition cylinder.  The
bezel needs to go first.

The key goes in the tumbler, the tumbler goes into the steering lock, the steering lock goes INTO
the column.

You should have a pretty chrome ring with black rubber that finishes off the the hole in the dash
where the key goes in. THAT is the estcutcheon. The black bezel is in the hole. The black bezel will
NOT fit thru the chrome ring unless you remove it.

Does the hole around the black bezel look crappy and unfinished?

Go here:
http://mercedes.thebenzbin.com/?year=1983&make=MB&imageField22222.x=38&imageFiel
d22222.y=16

Click on Steering.  Click on Ignition Lock Cover, 2nd item listed.    THAT is the chrome ring and
rubber ring.
Now click on Ignition Lock Cover. THAT is the black bezel.
Now click on Ignition Lock Cover above the pic, it will take you back to the list. Click on Steering
again. Now click on Ignition Lock Housing, 4th item listed. THAT is your steering lock. It is a T
shaped unit. The tumbler goes into the small end opposite the electrical plug. The long skinny end
goes into the steering column.