I looked at the OEM ones. The clockspring is the same on all of 'em. The buttons are different, because they have built in resistors. One circuit controls several buttons. The ACM interprets the resistance to know which button you're pressing. From what I can tell, each option requires a new ACM. It's odd, because the clockspring wires all terminate the same place with all options, except for 2, and they seem to switch per option. You really need to see the OEM diagram to get it.