Later 80's + speed sensor.

Speed sensor  for  most - CAREFULL.. NO RETURN OR PLAYING WITH THEN RETURNING Brand NEW SPEED SENSORS.... these have been 100% perfect. unlike older ones or cars with other related faults.  If you think as a few folk have that "its worth a try" to get one and fit it than say its faulty like yours.. please buy somewhere else..   These are brand new and never been used ever.

1983-92 T700R4, 4l60 MD8 Auto

check yours up against this image.