p.v.switches

[giandtb@mb.sympatico.ca]

On a 75- 351 ford motor - does anyone know about pvs (ported vacuum
switches) that sit on top of the intake manifold near the front. They
sense water temp. with respect to emissions via vacuum lines.
        
        I have a 3 port switch that i believe is Blue color coded, operating in
the 125 to 131 farenheight range. 

        I have a 2 port switch that I can't make the color out. 

        Any one know the color or the temp. range

                        thanks george