Product Details: 
Speedo Sender, 7/8-18thd Hall Effect, 16 Pulse 
Hall Effect Speedometer Sender 
Product # 5291 
Mechanical to electric speed sensor for use with all Auto Meter electronic speedometers. 
7/8" - 18THD, Hall Effect sender, 16 pulse per rev. Includes pass-thru drive for cruise control. Adapts most GM and Chrysler transmissions with speedometer cable output to work with Auto Meter Electric Speedometers.