One of the beauties of the Mercedes door lock system is that you don't have to pull the door panels, kick panels, or under-dash panels. Everything is done under the rear seat. Caveat: W123 and older cars need to have an electric actuator installed inside the driver's door and wires fished through to under-the-dash. That one was more work.

You can install the matching set of lock cylinders before or after, it really doesn't matter. You may find the keyless entry so convenient that you stop worrying about the mis-matched keys. If your vacuum/pressure pump and actuators are working correctly, the remote will lock and unlock everything.

Jeremy

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970