Topic: What's this part in my 70 Mustang?

[cool67]

I just bought a non running ,but wired about 95%,70 sportsroof It was a 302 automatic car. Anyway I've have several 69's over the years but I found a part on this one that I don't know it'd purpose.It is a plastic box about the size of an uninstalled single house swithbox. Part number on it is D0AF-9E718 and in yellow lettering it says 9L12V. It has 4 wires coming out of it (blue,red,brown and black)It is located on the inside driverside lower firewall. two of the wires go to what looks like a double sided theaded fitting to connect the speedometer to on both ends.It has to do something with the speedometer I would think. Any HELP?

[J_Speegle]

Should be a white  with a cover in a different color ( can't remember the different colors right this moment but they indicate the application)

This is part of the Dist-o-vac system an  emission system Ford used in some different applications that year. Should attach (as you mention) to the speedometer to get input as to how fast the car is going, to a temp sender located in the drivers side door jamb. With these two inputs the box controls the amount of vacuum and advance or retard  to the dist


Hope this helps

[DEWilson]

here is a diagram of it