I don't think you can swap the locks. The cylinder is attached to the small black trim piece on the door handle, and I don't think it can be rotated 180 degrees. I may be wrong. Anyway, to get the lock out, there's a small round plastic cap on the side of the door (the part of the door that's hidden when it is closed). The cap is perpendicular to the lock cylinder. Remove the cap, and there is access to a small socket head setscrew, maybe a 4mm hex. (Could be 3.) Remove that screw, put the key in the lock and use the key to pull the whole cylinder out of the door. There was another thread on this very recently, in the last week or two. Search for it, I think there were even some pictures.

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1987 W201 190D