Convertible quarter glass vs Hardtop

Agree, they're different. The convertible has the sharp upper angle where it hits the top frame, whereas the hardtops have a curved upper edge. As a side note, the '67 Dart hardtop quarter glass is unique. It's a press-on track type. The 68-up glass is a bolt-in. I don't think they did this with the convertibles, but, you may want to look at your RH quarter glass to see how it's mounted. If you swap all the internal pieces along with the glass, it would probably interchange, although I've never tried it myself.