W124 memory seats
 

I just bought a '95 E320 without memory position seats. Does anyone know what's involved in making them memory seats? I have access to a seat switch with the green memory button from another E320. I believe there's a module involved? Is it just a matter of installing this door switch and hooking up the module?

At first glance...
1) Replace seat switch with memory equipped switch
2) Replace seat switch harness that runs down to seat (memory has more wires)
3) Replace seat control module with one that is memory equipped.

There might be more as the system also ties into the steering column and has memory...

Additionally there are encoders/resolvers that are on the seat motors as well..these provide the positional data to the memory module. I am not sure if the non-memory motor had this, seems to me that they likely would not.

Your best best would be to go to the junkyard and get the entire seat, harness and switch, that way you'd have all the parts.