Power door locks
If I was to make these arm extensions again, I would make them longer and instead of having the two rods above and below each other, I would attach the original rod inboard and the solenoid outboard. This would give the solenoid more travel (which it seems to want) and it would also give it more leverage to overcome the spring. The spring I am talking about is designed so that when you pull the lock knob up it is sprung up and when you push it down it is sprung down. This spring is pretty strong and yet is not needed with the electric, as the solenoid will perform this function quite well. Because the spring is so strong I had problems with the solenoids not having enough power so I had to squeeze the spring with a pair of needle nose plyers to get rid of some of the tension. Don't even think of doing this without taking the door handle and mechanism off. It is not that hard and it gives you a chance to clean thirty years of crud out of the mechanism and lube it up again.
This picture shows the arm extension. I simply attached it with a single pop rivet through the hole that the original rod connected to. In order to keep it from rotating with the single rivet, I made a notch in the aluminum that fit the arm like an open end wrench. This left two ears that protrude on either side of the original arm where it makes the bend and keeps everything solid.