how to change the speed sensor on transmission on 1997 Ford Contour

It drives fine under 35 mph over that it dont shift right it jumps all around like its not sure to shift or not.

Asked by for the 1997 Ford Contour
As long as you have a speed sensor code, then go ahead, otherwise, it may be something else. There is more than one transmission speed sensor i.e. input and output, which one were you referring to?
The code read for trans range sensor but,they say that car dont have range sensor. They said its probably trans speed sensor which inputs motor speed to trans.