1973 C3 Temperature gauge sending unit

Hi,I hope everyone is enjoying their Holiday weekend.I had a question about which dark green wire should be used for my temp gauge.There is a wire that comes right out of the firewall(passenger side)and there is also a wire in a harness on the driverside(both dark green) they both seem to go to a sending unit,i'm not sure.I'm swapping engines and not sure which is which??Thanks for any help!

On my 72, the green wire on the driver's side goes to the temp sensor.  There is a green wire that comes out of a bunch of wires on the pax side and it goes to the A/C compressor clutch switch.

There was a temp sensor on the pax side of the engine (gone now) that was for the transmission controlled spark.

Adams Apple will be along soon with the wiring diagram...

Greetings, Depending on the type you have, it could be for oil pressure sender if both go to drivers side. 

I would try running a continuity test from the sensor to each one of the green wires and see which one is the one.

Thanks,That makes sense.I guess you use a 9 volt battery?

Thanks,Oil press gauge is mechanical.This thing has been apart for over a month but i'm pretty sure the passenger side sending unit is for the temp gauge and the driver side is maybe for a smog sensor?Looks like(the wire) hadn't been hooked up in awhile?Seems like there's been some yokels that have worked on this car in the past!

I guess you could do that but I was thinking of a extra long lead and using a VOM. The temperature sending unit on my '73 is located on the driver's side head.

Do you or did you have a sending unit on the passenger side?

I did, it was for the TCS which has been removed and unnecessary.

Temp sensor(single green wire) on driver side is for the temp gauge. Sensor (2 wire) on pass side is for the TCS(transmission controlled spark).