The gear is metal, about 4 inches long, and has a spline looking gear on the end that goes into the transmission and a small dime size sprocket looking gear that fits into a electronic part. I have tried a few transmisson places, they say dealer item. the dealers say it was discontinued in 1993.
91 dodge pickup on 1994 Dodge Ram 2500
go to this site http://www.transmissioncenter.net/speedometer_calibration_______va.htm and see if this is the gear your looking for.