Replacing Drums and Shoes on 69 Dart
The dimensions are in the back of the chapter on Brakes in the service manual. If you don't have a 1969 service manual, get yourself one. Nothing like info direct from the source. There's still occassional errors and ommissons but the most reliable source you can get. Service bulletins have been collected and posted at
The 1970 Hamtramck Registry Library Page (1965 - 1969)