The term has been around since the 40s and 50s. As too regional no it was/is nationwide. More likely cultural. The youth of those days were more accuztomex to it than their parents
Must be regional or something else because I’ve never heard “old man” used in any other context than as a father. I’ve lived in Florida and the west coast and traveled all over the US for context.
“The ‘ol’ ball and chain” is used for spouse, unfortunately it’s usually used for women.
At that age you should have heard it at least once in your life. Dunno maybe the 20 year difference between us is enough to prevent that kind of exposure
My old man
He's a singer in the park
He's a walker in the rain
He's a dancer in the dark
We don't need no piece of paper
From the city hall
Keeping us tied and true
No, my old man
Keeping away my blues