ka24de transmission question helppp

:confused: i recently mess up my 1995 240sx ka24de manual transmission and i bought a used one online when it arrive its seem very identical but mine has only one switch in the bell which is the reverse lamb switch without thinking about the speed sensor and the new one has two. this switch its in the passenger side between the od switch and the reverse lamb switch
i have done some research and i think its a 91-94 trany from a 240 and it says it is the top position switch but iam not qite sure wat function these has.... what happen if i dont connect it? does it matter or what should i do?