I have an 84 and although I've never needed rear sight components, I understand they're hard to find. The 84 and the earlier 82 used the same sight parts (I believe), so a newer 82 sight might fit. Not sure if the S&W parts will fit, but I've seen on other forums that people have used them with some modification. Again, I'm not positive.
We love pictures here (hint, hint), and I especially love pictures of older revolvers.
Welcome to TA from Cherokee County, Georgia.