That's what I used (repops). They came from Trim Parts and are absolutely flawless. Good chance the originals were never as nice.
There were some nice ones at first, starting in '68 and continuing to the '70/'71 Barracuda, '70/'71 Challenger, and many others. Then in '72 they went to the "corporate" side markers on many models. Of course, some models still had their own "integrated" markers (my '78 Cordoba had nice looking side markers, I still miss that car 20 years later.........). They also used them on the front of trucks up until '93 (I think). Never cared for them at all. They just look like a cheap, tacked on after thought. JMO.