Did Darts only come with the small wheel bolt pattern?

The reason I ask this is....I have a rear which I have confirmed is an A body rear and measures correcrtly from back plate to back plate. However, my wheels are pushed out much further to the outside than other Darts with the same wheels on it and backspacing. It seems that the brake hubs are wider than a standard Dart. Were there different brake/hub widths that would require a bit of a longer axle? If not why are my wheels further apart than my buddies Dart with the same set up? Ideas? Thanks