Looking at my wiring diagrams, on your 93, the combination meter(gauge cluster) shows that your truck has the 3 wire Vehicle speed sensor wires coming from the external sensor. So you should see the black plug with three wires coming from the end of your TC. I would unplug it, and pull the bolt off that holds the sensor in. Check to make sure that the nylon gear is intact. If you can, which I am not sure. try to stick your finger in the hole, and see if you can spin the gear that is on the output shaft. If you can that is bad. If you can't then it's something else whining in your tranny/TC.
Hope this helps ya
