Hello Shorod,
Thank you!
Finally, yesterday I had the chance to spend some time on the car and located the VSS. In my case, Taurus 1996, V6 Duratec 24 Valves, you can access it on the passenger side by following down a two-wire (kind of pink color for one) plug attached to a round black plastic stuff (like a cap) on top of the belts. you can feel it (not see it) close to a big and polished round stuff. There is (in my case) a cover on it (to protect it).
Now, I am unable to perform the test you suggested me using the speedometer cable. Because it appears that I do not have a speedometer cable (I confirmed this by removing the dashboard: only 3 plugs of many wires arrive in its back). I have an electronic speedometer (though display is not digital).
I did not remove the VSS yet because:1) I would like to know if there is a simple way to test such electronic speedo, and 2) it is also difficult (no room to work from the top; need a long extension to be able to apply enough torque to unscrew the 10 mm bolt).
Thanks again for your time spent on this and your advice!
Alf