At the beginning of the Tudor brand, and a long time into its history, Tudor used Rolex cases for its watches.
As such, the serial number of Tudor watches are found in the same place as they would be found on a Rolex watch, they are engraved between the lugs at the 6 o’clock position engraved into the case removing the bracelet.

The serial numbers of Tudor watches are more complicated to date than the serial numbers of Rolex. There is less information available about Tudor.
Modern Tudor watches have the reference number and serial number placed on the undersides of the lugs, so that you don’t have to remove the bracelet.

The list here after will help you find out the approximate production date of your Tudor watch.