I have a 1983 delta 88 with the 5.0 307 motor and there is a sensor or switch right next to the coolant temp switch and i can not figure out what it is. The reason for wanting to know is i installed a new temp switch and in the process i broke the plastic part off the unknown sensor/switch and would like to replace it. I dont have a pic but will be posting one in the morning, i just dont feel like going out in the cold to take a picture tonight. It has a one wire ring terminal-like connection going to it.

 

One goes to the ECM, the other for the gauge/temp light if I remember right.

 

^^^This. The one closest to the t-stat is the idiot light sender. The other one is the ECU coolant temp sensor. To the OP: The CCC system on the 307 is VERY sensitive to adjustments. Do not arbitrarily try to "adjust" anything without following the Chassis Service Manual TO THE LETTER. Otherwise, you will just make is worse.