Recently I fitted remote central locking to my 740 which required the fitting of a lock motor in the drivers door.
Subsequently there was a metallic rattle from the door which I was sure was a lock actuating rod vibrating.
After removing and refitting the door trim several times it was finally traced to the metal cable clip shown below which was loose in the panel, I cured it by glueing it in place with a blob of RTV sealer.

Well worth checking when you have the door trim off, it might save a lot of work later.

Colin.

I need to chane my driver door regulator. How do you install the remote lock and where did you buy it??

The main problem is that the standard central locking does not have a lock motor in the drivers door.
This door unlocks manually and operates a switch which triggers the relay to lock/unlock the other doors.
The standard advice given is to get the lock motor and linkage from the passenger door of a similar car and fit it to the drivers door.
In my case this was not an option so I bought a Microscan remote lock kit and one of their universal 2 wire motors. For details Click Here
This is a UK site but these or similar bits should be available locally to you.
Mine is the later model 740 with an enormous switch assembly fitted directly to the lock this gets in the way of the linkage from below up to the lock.
(I yours is the earlier type the switch is remote from the lock which would make life easier.)
This was solved by removing the switch completely, this had the added advantage of leaving me with 2 spare wires in the loom which passes through the "A" pillar which I could use to power the lock motor. This saved the hassle of getting extra wires through the flexible conduit between the "A" pillar and the door.
The motor bolted to existing holes in the door with a bracket made from the perforated srip provided with the kit, the rod goes straight from the lock motor and clamps to the lock button rod. See pics below for mounting details

(This is a RHD car so yours will be a mirror image of this.)
The relay/reciever was fitted behind the trim panel in front of the "A" pillar by cutting into the loom at this point and splicng into the existing wiring.
The instructions for the kit show the unit switching the other lock motors direct but, having a mistrust of the ability of cheap electronics to switch the currents involved I wired mine using the the reciever to trigger the existing C/L relay.
If you do this and get stuck with the wiring mail me and I`ll go into more detail.
Colin.