Did Darts only come with the small wheel bolt pattern?

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

I'm not sure about 8.75" rear. In the case of the 7¼", the backing plates for the LBP axle are a little bit different which requires a longer axle shaft than the SBP. What it means is that even if the rear is a 7¼, the rear track on the LBP is a little bit wider. These parts can not be mixed and matched.

If all the rears are the same, suggest check for wheel offset differences.