This is the Cable Speed Sensor (E2AZ-9E731-A) used on early (pre-'87) cruise systems to generate a VSS. It's in the middle of the speedo cable (E3MZ-9A820-A), usually beside the brake booster, but they always seize up inside. They produce 6 pulses per rev, just like the later style that mounted in the tailhousing at the bottom end of the speedo cable.
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