Tranny Sensor Help

OK, I've never looked into what the tranny sensors are for or what they do. So can someone tell me?

Also, Here are some pics I took. I have two trannies. One from a 84 CA20E car and one from my 85 turbo. The nice looking one is from the 84. The two circles in the first pic are where the sensors would go.

http://img.photobucket.com/albums/v288/westside27375/Car%20Pics/DSC00504.jpg

http://img.photobucket.com/albums/v288/westside27375/Car%20Pics/DSC00506.jpg

I wanted to use the 84 one when I put the engine back into my car, however today I came across this little problem. It only has two spots for sensors and my 85 tranny has three and there in different spots as well...see pics.

I know the very easy solution is to say **** it and just reuse the 85 tranny which is what I'm going to end up doing, but say I wanted to try and adapt the 84 tranny in what would I need to do?

Thats weird.....my 84' turbo has 3. On mine, from the bell housing back, the first one is Reverse lamp switch, then top gear switch, and the last one right above where the spedo pinion goes is the neutral switch.
Have you looked.....maybe there is another harness plug tucked in somewhere along the wiring harness??
Looks like in your photo on the '84 tranny, you have a spot for the neutral switch, and the reverse lamp switch

Ok, according to the FSM,
starting from the engine side to the diff side
1 - reverse light (backup switch)
2 - OD switch
3 - OD switch

But that's for all FSWB trannies, no difference between years in the manual

If it's a 5 spd.....you won't have an O.D. switch....right? Atleast mine doesn't.
I just replaced all 3 of mine about 2 years ago, and they were the 3 I listed above.

Where is the identification number on the tranny? I think the 84 may be something else.

BTW, My car does have three connections for the tranny since it is an 85 turbo....hence why my 85 tranny has three sensors.

Thanks keith and mr.200 for letting me know what the senors are for.

EDIT: Just went out to look for some markings and noticed a few differences...on the side of the 84 tranny there is a marking "X71B #1" and on the 85 in the same spot "CA71B". I suspect that the 71B refers to the fact there both the same tranny, however internally I think they have different gear ratios and on the out side they look a little different.

Ok, so I'm going to be difficult. I want to put in that 84 tranny becuase of the gear ratios in it...better 5th gear.

Anywho, Since it doesn't ahve a place for a top gear sensor could I just wire in a switch and flick it on when I'm in 5th? Or should I leave it alone? Does anyone know what the purpose of it is?