Having a fit with the passenger's drum on '67 Dart

Check the adjusters......I think that the 10" drums have slightly bigger adjusters and you may have that installed on the side that is giving you the problem. Also check the bar (I think its called an equalizer) that goes between the shoes just above the axle line. The 10" drums also may use a bigger bar and if any of those parts are installed on your 9" drums, that could be your problem.