So when I did this on our '70, I couldn't find anyone either.
I finally took the broken one and fabbed up the wire and it's guide using some plastic from a bondo spreader with a hole drilled in it. Glued that to the frame of the broken indicator and ran a wire thru it to the clip.
Florist wire works darn good.
When I was done, I received an email from a guy with a salvage yard in the South East, and he had an intact one that I wound up buing, but the repaired one also would have worked fine. Can't see it once it's in, so the "originality" wouldn't have been an issue IMHO...
If you don't find one, you might try repairing yours.
-curt