What does this clutch switch do?

Im in the process of trying to figure out how all the components work on my 4 speed a body pedal assembly. In playing with another rebuilt pedal assembly I bought off this site I broke off the plastic stop tab on the end of this switch. I have enclosed some pics of it. It looks like the switch is depressed when the clutch pedal is pressed and releases when the clutch is raised. What is the purpose of this switch. The assembly and the car it is going into is a 67 4 speed a body. Where can I find a new switch and how can I remove the old one. Are replacements inexpensive? I played with it a bit but it seems that the switch is set in the bracket pretty tight. Was this switch on all 4 speed abodies or only certain years?

Carl