At a local salvage yard I found a 1972 Pontiac Grand Prix with power door locks which will work in a Skylark since the Grand Prix is considered an A-body like a Skylark. Unfortunately, the top rubber boot was ripped on one solenoid so water entered and it was rusted in place. I took the solenoid anyways since the bracket was the important part. The solenoid can be found in all GM cars with power door locks from 1970 to 1976. Luckily I found a 1972 Electra nearby that had power door locks which were in excellent condition.
After I got home, I compared the two slightly different solenoids and noticed the brackets are almost in the same location except the Electra's solenoid brackets are mounted a 1/4 higher (toward the actuating rod) versus the original A-body part. I drilled out the spot welds being careful not to drill through the solenoid case. I transferred the A-body brackets to the good solenoids and spot welded them in place. All that was needed was to run the wiring and install the switches. Before I did any installation work, I checked out the wiring and switches. The wiring needed to be rewrapped and a splice needed to be repaired properly before I could use the wiring harness.
Before I rewrapped the wires, I used a cloth dampened with some mineral spirits to wipe down the wires which removed all the old wrapping residue and gave me a better view of the wires to check for any damage such as nicks and/or cuts. You do not want to install the harness as removed from the donor car because a lot of work is involved and if a short is present it is more difficult to find once it is installed in the car. After finishing the harness, I checked out the switches with a multimeter to make sure the contacts were good and not burned out.
After removing the door panels, kick panels and dash pad, I was ready to install the power door lock system. Since my car already has power windows, the wiring follows the power window wiring. If you do not have power windows, you will need to install the flexible rubber boots that go from the door to the cowl. The holes for the boots are prelocated by dimples and a door hole saw will cut the necessary size hole for the boot. Take your time with the door hole saw and spray some WD-40 on the saw to keep it cool and lubricated. The holes for the solenoid mounting brackes are also prelocated by dimples on the door jamb surface. If you look closely at the bottom of the door, you will see three dimples arranged in a triangular pattern. Drill those dimples out with a 5/16" drill bit. The actuating rod goes into the door latch just below the point where the key cylinder attaches to the latch. The driver's door actuating rod end has to be flattened with a hammer slightly since the hole for the rod is not a perfect circle. Once you see the shape of the hole, you will understand why the rod needs to be flattened. Connect the solenoid wires to the solenoid then slide actuating rod with solenoid into the door latch and gently lower the solenoid into position with the three holes. If you do not connect the wires first before you mount the solenoid, you will not be able to connect them since access is limited.
After mounting the solenoids, run the wires through the door boots and into the dash. Leave the orange power wire next to the fuse panel. Use a piece of string routed over the gauges with a coat hanger to pull the wire harness over the instrument cluster. The driver's side harness will end up behind the radio and the passenger side harness will plug into it. Plug the orange wire into the fuse panel marked "bat". All that is left to do is locate the switches in the door panel, mount and connect them to the harness.
Some door panels already have the switch location prelocated on the back side of the door panel. It is partially stamped through the back fiberboard with a broken line. Use a utility knife to cut through the panel and insert the retainer and then the switch. If you door panel is not marked, the switch is located 17" from the panel bottom edge and 12" from the front edge (closest to the fender). If you lay out these dimensions on the door itself, you will be in the middle of a small square hole which is where the switch is located.
Make a test run before you install the panels, sill plates, etc just in case a wire got nicked and grounded or came unplugged. The total installation time is about two hours if your car already has the door boots. If not add another two hours for removing the doors, drilling the holes for the boots, rehanging the doors and aligning them. The installation is not difficult just take your time and be careful when putting your arm inside the door since the openings have sharp edges and it does not take much movement to get a cut. As a prevention to arm cuts, place duct tape around the opening's edge to dull the sharp edge.