Advice needed on installing AMD full quarter on 70 Duster
I'm unsure which brace you are referring to removing. My 70 duster has pop out rear side windows, as opposed to full vertically moving windows like a 72 valiant we used to have. I'm not sure what your demon has. Here is a picture of the area, the brace which the quarter attaches to runs under the roof sill. I can't tell in your photo whether you removed part of the roof sill, but I chose to leave it in (maybe that was a mistake on my part).
