Coolant temperature sensor question
 

My friend has an 85 GMC suburban with a 350 engine, original setup. He needs to replace the coolant temperature sensor that is located on the thermostat housing that has a single lead coming from it . The several part stores that he checked with all sell sensors that have 2 leads, He noticed they sell pigtail kits that connect the senor. Question is, is this the right part?
Note, this is NOT the temperature sensor for the gauge, but is actually tied into the carburetor to control the fuel enrichment pump.

Yes, you should have 2 leads on it. Perhaps one of the old ones broke off or the wrong switch was installed at some point. The temperature switch in the thermostat housing is for the Dual Capacity Pump Solenoid in the Quadrajet. It supplies the positive (+) DC power.

+ in, + out of switch, then + into solenoid in the carb.