Thermostat switch wire color and connection help needed.
 

I have a 1969 250/8 that I am having trouble finding the electrical connection for the thermostat switch (212 oC). I have the connector knob that attaches to the switch at the thermostat housing that is attached to a black wire but can't seem to find where it connects to the electrical system. From my research I think it connects to the relay box #5 by the 2-way and 3-way vacuum switches and I think it connects to pin number 6. But the wiring scheme I used seems to tells me that it is a brown wire with a black strip. The only wire that isn't connected to anything is a black wire with a blue stripe. Is this the correct wire?
I would appreciate any help that anyone can give me on the subject. Thank you in advance. Peter