Replace hyphen with en-dash only after 4-digit years

[ohrenkino]

The examples can be found here in the forum, e.g. here:

Help with an action to change two-digit years to four-digit years

Can anyone help me with an action that will look at the year, determine if it's four or two digits, and if it's two digits, prepend "19" to those digits. I need four digit years to remain in place unaltered. I figured out how to write the year to a custom field, prepend the "19" and then write that back to the year field. That doesn't work because my four digit years wind up being six digit years such as "192017". Any help is appreciated.

I found this thread with the search words "digit year".