On many Ford stereos, you can display the serial number on the screen without removing the unit from the dashboard:
Alternatively, the serial number will be printed on a label on the back of the radio unit. You will need to remove the unit from the dashboard to see it.
This page now searches the full database of V- and M-series Ford radio codes. All for free.
The codes apply to Ford 3000, 4000, 4500, 5000 and 6000 stereos found in Escort, Fiesta, Focus, Mondeo and Transit models.
I built it because it was a pain finding my own code when my car battery died. I hope it's a help to others.
Feel free to buy me a coffee.
Or perhaps it's time to upgrade to a stereo with Android Auto / Carplay?
Some options on Amazon.