The 1983 300SD will NOT lock/unlock the driver's door with keyless entry unless modifications are made; there is NO vacuum actuator in that door; only a switch.

You could run a vacuum line to the driver's door and add a 1985+ actuator/switch, or do what myself, and others, have done, and "piggy-back" an electric actuator to the driver's side door lock which will then actuate the switch and run the system just the same as if you were using your key.

Pindelski.com (moderate subscription cost; no affiliation) has a complete "how-to" on it.

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The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)