560SEL temp guage not working & vacuum issue
 

Looked at temp sensor on thermostat housing and there are two sensor, one with 3 prongs and the other with just one. I've heard that the interior temp guage is run off of the sensor with one prong but there are only 2 wires going to other sensor, can't find third - did I get the wrong sensor?

Also, the yellow vacuum fitting on driver's side firewall - I believe one of the lines coming out of it goes to the hose underneath the air cleaner, anyone have an idea where the other one goes? Last question - where does the "vacuum amplifier" attach? It's sitting loose on intake manifold now.

Thank you