The issue with the 123 and earlier cars is that the door lock system is entirely mechanical, relying on stored vacuum and a physical door lock vacuum switch. You would literally need a module in the door or trunk with physical switchover valves to mimic the behavior of the master lock switch. Your SDL has an electric pump in the trunk for the door locks and works on a different principle.

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Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)