cab corner / rocker fit on these truck's is horrible , and so is every other piece of sheetmetal , anywhere that one part is supposed to align with another on these truck's it is off , door's stick out , tailgates stick out , door to fender gap's are awfull !!!
but here is the good news you can fix it !! I almost got upset with my 67 because of these alignment problem's but I just fixed them and went on about my day ,, here is my 67 when I was working on it , if you would like some better up close pics of rocker and door gaps I can take some ,, here is just a few I had saved