67 Dart Build Triangulated 4 link & Mini Tub

Did you start with a 68-70 B rear axle?

If so, The housing started out at 54 15/16 call it 55" and took off 7.5", it should have been 47 7/16 or 47.5" flange to flange.

The wild card is your disc brake rotor hat thickness.

Yes I used a B Body Housing on mine if that helps!