Try putting up a “WANTED” ad for them and be patient. A set will eventually turn up. There are a few guys on this forum who part out cars and they can keep an eye out for them for you.
They were an option item for new cars. I remember guys removing them in the late 1970s. My Duster still has them and I like the look.
Thanks for the advice. My car needs something to break up the green, I figured that rocker trim along with wheel well trim would help class the girl up a little.