Don, the biggest obstacle to putting duals on an early model Ford is the exhaust pipe clearance to the clutch pedal, and going through the hole in the frame. This is true whether the manifold exits front or rear, and actualy kinks up the pipe worse with the rear exit. For the clutch pedal clearance, you must heat and dent the pipe to clear the elbow on the pedal. Take care not to collapse the pipe to the point of seriously restricting flow.