Factory heavy-duty suspension on 66 dart

Syleng1 said
Add: 8-3/4 rear axle for towing or 4 speed.

THe Rallye Package for the Dart and the Formula S and Suspension package for the Barracuda's and Valiants include HD springs, shocks, sway bar, torsion bars, and other options but it does not include a 8 3/4 rear.