Stewart Warner Corp. Speedo ID

[Paultrehberg]

What year is a Stewart Warner speedo with black ink stampings on the back. 509DWK9. Also has NC stamp.The speedo also has a magnet with two wires mounted on the side opposite the reset dial. ( Could not figure out how to post a picture ).I sent it to Napierala, he cleaned/looked it over ( only$90) sent it back but did not provide any info on it.

[Rubone]

That isn't a magnet, it is a solenoid for the handlock as used on Police units. See codes here..
http://www.ruiter.ca/mc/info/SWSpeedoDating.html