so i started the unholy breakdown of some things to do the usual maintenance replace the alt and some pulleys and i found this , there's a sensor wire on one and the other looks like it's supposed to be there but isn't, anyone know what this is and can i do without it?

 

That is an additional temp sensor for the automatic tranny control system. If your car is an auto, it should be hooked up. Otherwise, that thermostat housing came from a car with an auto tranny.

Dale