A little general knowledge help

A 1972 Dart Swinger was originally equipped with the small bolt pattern (4") with either drum or disc brakes. Six cylinder 1973-1976 A-bodies (1976 models built prior to January 1, 1976) with drum brakes were still equipped with the small bolt pattern (4") and 7-1/4" rear axles. All disk brake equipped 1973-1976 A-bodies were equipped with the large bolt pattern (4.5") whether 7-1/4" rear axle or 8-1/4" rear axle. The 8-1/4" rear axle was introduced in the A-bodies for the 1973 model year.